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Thread: the end all tire (and wheel) thread

  1. #1

    the end all tire (and wheel) thread

    as most of the information is available, i will compile it here.

    tires are the most important part of your car. that's it. period.

    that said... here's your choices for the evo.

    first we'll talk size. i've said many times in many threads the same information. but i will repeat it here one last time.

    tires in general like a trapezoidal pattern. this makes for stiffer sidewalls, which means quicker turn in. however a bulged setup will break away more evenly, gradually and will heat up a tire faster. fast heat up is beneficial in certain types of comepetion (autocross). you can run a combination of the two as they do in japanese racing.
    ____
    /.......\
    |||||||

    |||||||
    \____/ this is a trapezoidal pattern.

    here's my favorite tire calculator, lets you compare two. http://www.net-comber.com/tirecalc.html

    herein we also talk about tire clearences which involves wheels. here's an explanation of offset from tirerack: http://www.tirerack.com/wheels/tech/...jsp?techid=101


    17s: the factory wheel is 17" in diameter. the factory tire size is 235 45.

    17s are cheap, check out 18 sizes on tirerack and you'll see the price hike is formidable, sometimes up to 100 PER TIRE! that said if you're a track junkie you will want to stay in 17s until you step up to slicks or offerings in the 9.5" wide and beyond tire class.

    255 40 is your best bet. this tire is available from almost all tire manufacturers on every tire series that is made. this tire size is best run on a 8.5-9" wide wheel with a +35 offset. that said it will fit a 8-9.5" wide wheels i don't know about 10", even tho it's theoretically possible by the time people go to 10" wide wheels they're not ****in' around with lowering springs and fender clearence.

    that said let's move on to other sizes in 17.
    245 40 is a great size especially since this is actually even more available than 255 (255 covers performance tires, lots of all seasons and stuff don't come in such an aggressive size, but they come in 245!). 245 will allow you more fender clearence, if you want to slam your wheels to the edge of the car (+30-+25 offests for 8.5" and 9" wheels) and lower then 245 is a good tire for you. this tire is best run on an 8.5" wide wheel but will do plenty fine on the stock size which is 8" wide. this size tire can be stretched up to 9.5" wide wheels.

    that said the only other size in 17 you should want to adventure with is the stock size, however be wary that many tires are not as stiff as stiff which means the tire roll over and turn in characteristics will suck for such a tall tire.

    now for the more "fun" sizes. i will say this once, if you run fun sizes, be prepared for fender work. don't be a wuss, just do it once and never worry again, i recommend shaving because you don't have to heat the paint and worry about cracking, you just touch up the areas that are not visiable to the exterior of the car. . end of story.

    275 40 is larger than the stock tire outter diameter. you will encounter rubbing. fender for sure, maybe lower control arm in rear depending on your wheel offset. you might get liner rub in front too. allow the liners to clearence themselves (let the holes rub, don't tear out the liner, tearing out liner is bad for air flow and also bad for your oil cooler and your door jam as rocks get tossed everywhere). once the liners clear themselves you can get some roof caulking and seal up the holes as you see fit.

    18s. 18" tires are desireable because the more performance oriented tires offer wider sizes in 18. in 18 you can go up to 355 in width on some crazy tires.

    if you are running 18s i don't recommend running a 235 series tire, this tire will either be too thin which will hurt your 18s and also make for a horrendous ride, or too tall. that said you can try to run 235 40 (thin). 235 45 is too tall and not worth even trying

    245 is well run in either 35 (thin) or 40 which is a lil bit tall (but within reason). keep in mind that if you run a tire stretched the overall diameter is reduced slightly. that said, running a 245 40 on a 9" wheel will get you a good size compromise. 245 is similarly best run on an 8.5" wide wheel but will do 8" wide. this size tire can be stretched up to 9.5" wide wheels. you must be a lil more careful with 18s as far as offsets go... a few more mm or a few more degrees of camber are necesary for everything to clear the same as 17s.

    255 35 is the ideal size for 18s. this size is a little hard to find in most tires, but this is the perfect 18" tire size. it is well run on 8.5" but iw ideally put on a 9" wheels, it can also be stretched to 9.5" and if you so choose, beyond that. this fitment also incurs no rubbing with the right offset +35.

    265 35 is a great amount of rubber is is offered in many r comp series tires. that said you will have to roll in the rear on +33 and smaller offsets. there have been few cases of +35 clearing with no rubbing. that said you can also try stretching the tire but this will get you less benefits at this size as the wheel and what is required to make it fit will likely outweigh the stretching benefits. you may also encounter a tiny bit of liner rub if your liners are not perfectly molded to the car.

    275 35 is a great size and you will run in to the same fun rubber problems mentioned for 275 40 17 even tho it is smaller in diameter than stock.

    285 30 is smaller than stock, but it's wider than crap so you will also get some rubbing. this is the largest "sane" size and that said it's quite insane. until you go to unconventional slick numbering, it doens't get bigger than this without a body kit.

    other sizes that can be run on evos with a wide body. 305 30 18 is the most common with the apr widebody.

    tires i don't recommend running, 245 45 17 and 255 40 18. these are tall will rub and don't give you enough grip to justify the rubbing.

  2. #2

    Re: the end all tire (and wheel) thread

    TIRE REVIEW SECTION will state only recommended (common and known to fit) sizes to be run on evos of the appropriate wheel size.

    common STREET tires to run on the evo. street tires include maximum performance tires, also known as summer tires. tires that do not have too much regard for wet performance. street also includes snow tires for those who need that wet performance, even in competition this is important, wet autocross tires can get you wins.

    street tires will light off very quickly and not hold heat very well, they come fully tread which means tread squirm is an issue and may do well shaved, however that eliminates the purpose of running a street tire. that said they will also chunk when overheated due to full tread blocks and the heat that they retain.

    many street tires do not have the same sidewall characteristics as stock so running the stock size may introduce lazy steering response, careful profile choice is more important in these types of tires. also due to sidewall softness or hardness, ride comfort is affected and the sidewall height and hardness may effect wheel ding succeptability. choose sizes wisely.

    FALKEN AZENIS RT-615 is the best bet for multipurpose street use. this tire has great stick, great tire sidewall stiffness (compareable to stock in the right profile and right tire geometry, stretched). that said it's wet performance is similar to stock (bad). it has quick light off characteristics which means it will warm up fast for autox hence the autox favorite. they're cheap they're in the right sizes for 17s. that said this is not the ideal track tire as the overheat quickly, at autox people can cool their tires with water between runs but there is no such luxery in roadrace. with that in consideration, if you have a sufficiently light car and sufficiently wide tire you'll never notice the heat. but if you drive an evo and run 255 you will get them greasy. these tires are ASYMETRIC so can't be flipped on the wheel.
    comes in
    245 45 17 (i only add this not recommended size because autox stu competitors may be interested in this maximum tire size)
    255 40 17,
    235 40 18,
    245 40 18,
    275 35 18.

    BF GOODRICH KD is bfg's best offering for max performance tires. that said it's wet performance is decent, better than stock but it's not a wet tire, so it will not touch a blizzak. the dry performance however rivals that of the stockers, which is what everyone is looking for. that said they're not cheap, only several tens cheaper than stock, but they come in more sizes and they come bigger and last much longer. these tires are ASYMETRIC so can't be flipped on the wheel.
    comes in
    245 40 17
    255 40 17
    275 40 17
    245 40 18
    265 35 18
    285 30 18

    YOKOHAMA ADVAN AD-07 NEOVA. this is the tire most similar to the stock evo tire available in different sizes and a revised tread pattern. they're expensive, last as long as stock tires, wet performance is better than stock and better than such alternatives as the rt-615. this tire makes a little bit more dry grip and also rides better daily. they light off fast just like stock. stiff sidewalls just like stock altho maybe a little less responsive, this most likely can be remedied wtih a better profile choice. they will hold their heat but not as long as r comps. the stockers seemed to hold their grip to the belts, hardly anyone has run these to the belts yet tho... i would guess that these are similar. SYMETRIC like stock.
    comes in
    235 40 17
    245 40 17
    255 40 17
    235 40 18
    265 35 18
    285 30 18

    MICHELIN PILOT SPORT PS2. this tire is prolly the best all around tire. it offers the most sizes, great wear characteristics (far beyond stock), good wet performance (comparable to neova) and great dry performance. the sidewalls are weaker than stock but will thus create a more comfortable ride. like all michelins it's it very very expensive. the tread pattern is very nonconstant which makes for some tread squirm. this tire will likely not outperform a more dedicated tire like the kd but with such all around performance it's hard to not look at twice. these tires also take quite a bit of heat just like other michelins and as such will last a few more laps than stock at the track. also since they can take some heat they'll be at home at autox too. ASYMETRIC not flippable.
    comes in
    235 40 17
    235 45 17
    245 40 17
    255 40 17
    265 40 17 < oddball size
    275 40 17
    235 40 18
    245 35 18 < oddball size
    245 40 18
    255 35 18
    265 35 18
    275 35 18

    BRIDGESTONE POTENZA RE-01R. much thanks to x838nwyfor an awesome review and helping out with this community tire project. this tire is bridgestone's flagship street tire offering. tread pattern is a bit remeniscent of the neova. in stock tire size these tires are a bit lazier than the stock tires but the ultimate grip level is higher than that of stock (for the same size). braking characteristics are better than stock (probably due to higher level of ultimate grip) and the break away characteristics are very progressive (possibly due to rouded shouldering from the factory, however these tires ride quieter. the weight is more than stock but i never nit pick when it comes to a good tire ;]. all this said the wet performance is good in autocross conditions. price is also similar to that of the other highest performance street tires.
    comes in
    235 40 17
    245 40 17
    235 40 18
    245 40 18
    265 35 18

    BRIDGESTONE POTENZA RE050A these tires are related to the stock scooby tire which is rumored to be the stiffest street tire made. in all respects this tire is very similar to the stock advan, it is severals steps higher than an s03 but it's sort of targetted as a specific car replacement tire where the s03 is a general replacement tire. wet performance is better than the stock advan. ASYMETRIC.
    come in
    235 45 17
    255 40 17
    245 40 17
    255 35 18
    265 35 18
    275 35 18

    HANKOOK VENTUS R-S2 Z212. this tire competes directly with the rt-615, that said it comes in more sizes, it's cheaper and rumor has it that it will take more heat than an rt-615. they're targetted at autocross practice crowd and they will perform well and light off quick and may even be competitive once shaved. sidewalls are not as stiff as the rt-615 or stock, but the tread patter is remeniscent of tires twice its price, however the large void areas likely mean it's a better rain tire compared to the rt-615. the ultimate level of grip on these tires is very good but could be due to the slightly wider nature of all hankook tires, this particular tire is SYMETRIC.
    comes in
    235 40 17
    235 40 18
    265 35 18

    KHUMO ECSTA MX are khumo's flagship street tire. khumo is probably more focused on the opposite ends of the spectrum, leaving the performance street tire class a bit wanting but this is their offering and it's not horrid. these tires have huge divided tread blocks which will cause a lot of heat and a lot of squirm. but most of the autocross guys will tell you that these get faster and faster until the belts show! because of the tread blocks the wet performance is very good, up there with the ps2 and because of how deep the tread blocks are these tires will last almost forever. all out grip is less than that of the stock tires, but can improve once shaved significantly. sidewall stiffness is also a little lazier compared to stock. where you can't beat these tires is the price, they're cheap and they last forever and they're SYMETRIC, flippable.
    comes in
    235 45 17
    245 40 17
    255 40 17
    275 40 17
    235 40 18
    245 40 18
    265 35 18
    275 35 18

    TOYO PROXES T1-R. these tires are for the person that doesn't care about ultimate performance, they are toyo's replacements for the t1-s. if you buys these guys you're lookin' for long tread life, great wet performance and generally civil performance (that means they ride soft with soft sidewalls and they'll squirm when you beat them and let go of the pavement like wussy ***** while making tons of noise). these guys will basically do better than all other previously mentioned tires in the wet. they'll also last longer than all, rivaled perhaps by the ecsta mx. these tires are also cheap. and at the end you can do awd burnouts with them and not feel bad. these tires come in many 'lo pro' sizes so you can slam your ride and run around euro style. these tires are SYMETRIC and hence flippable.
    comes in
    245 35 17
    245 40 17
    255 40 17
    265 40 17
    235 40 18
    245 35 18
    255 35 18
    265 35 18
    275 35 18
    285 30 18

    GOODYEAR EAGLE F1 GS-D3 these tires perform very well in the wet. this is most likely because of all the void area in the tread pattern. that said, the sidewalls are soft at best and the dry grip is less than stunning. they're also not cheap in larger sizes. i personally can't recommend these tires like many of the other lower tier tires in this review (actually all below this one excluding the blizzak which has its purposes). hey... at least the tire is quiet and SYMETRIC and comes in many lopro sizes.
    comes in
    235 40 17 (thin)
    235 45 17
    245 35 17 (thin)
    245 40 17
    255 40 17
    275 40 17
    235 40 18
    245 35 18
    245 40 18
    255 35 18
    265 35 18
    275 35 18
    285 35 18

    TOYO PROXES 4 this is a step below the t1-r. the t1-r will actually grip fairly well when you heat it up and you could probably last a track day without destroying them completely, you could even autocross on them on a wet day with really good results! the proxes4 however will do none of those. this is a 'civilian' tire, it's just gonna get you to and from work, keep you from hydroplaning in the rain, be quiet on the road, give you that nice soft ride.
    comes in
    235 45 17
    245 40 17
    255 40 17
    275 40 17
    235 40 18
    235 40 18
    245 40 18
    275 35 18

    BRIDGESTONE POTENZA SO-3 POLE POSITION. these tires are similar to the t1-r but lie somewhere between the t1-r and the proxes 4.
    comes in
    235 40 17
    235 45 17
    245 40 17
    255 40 17
    265 40 17
    235 40 18
    245 40 18
    255 35 18
    275 35 18

    DUNLOP DIREZZA DZ101. these are basically similar to the t1-r, but the t1-r rules this class of tires.
    comes in
    255 40 17
    265 40 18
    255 35 18
    275 35 18

    FALKEN AZENIS ST-115. favored by drifters because with low horsepower you need both lack of grip and expendable rubber to slide around town. these basically have the same description as the t1-r but they're not as good in the dry as the t1-r. SYMETRIC.
    comes in
    235 45 17
    245 40 17
    255 40 17
    235 40 18
    245 40 18
    255 35 18
    265 35 18
    275 35 18

    BRIDGESTONE BLIZZAK WS-50. these are the ultimate winter tires. they only come in one size that fits the evo (stock fitment). they perform in rain, sleet, snow and ice. no tire is a miracle worker but these are made for the worst conditions. short of a dedicated rally/snow tire with studs it don't get better than this for less than 200 a pop.
    comes in
    235 45 17

    R COMPOUND TIRES. these are the race spec tires that people will run for competition purposes or zealous street use. they range from the mild all purpose ra1 to the wild full slick hoosiers that are a joke when it comes to being approved by dot. r comps are dynamic, they will harden with heat cycles. this means if driven on the street daily they will get hard and take longer to heat up and also possibly last longer. i will not talk too much about turn in characteristics as most r comps have great sidewall stiffness. this means that they're a bit ruffer on the road but also if you get wider tires you get more trampoline effect and it's less harsh so it's a good trade. r comps are also more dependant on operating temp, so be careful on cold tires.

    TOYO PROXES RA1 is the most common r compound tire found. for the performance it's a steal. light off characteristics are good, usually less than 1 lap of a 1:30 track when they're full tread. this is the track monkey tire. this is also the zealous street user tire. did i mention they're cheap? the ra1 is the the standard when it comes to rcompound tires. as with many rcomps the ra1 comes with shallow tread and has a significant amount of rubber left after the tread blocks are gone. these tires are thus best shaved and will fair bad weather if you're super slow (however in slick form they should see only dry pavement use). they also retain street tire like noise when breaking away which makes them very "forgiving". these are SYMETRIC and can be flipped. these tires last long when it comes to track days and they're unshaved.
    comes in
    235 40 17
    255 40 17
    275 35 18
    305 35 18

    NITTO NT01. these tires are similar to the toyo trampio 888. fast, soft, sticky. they will not last as long as ra1s, but (since nitto is the same company as toyo) this is toyo's newest offering to bridge the gap between ra1 track monkey tires and the hoosier class rubber and are seconds faster than ra1s on a typical. tho these tires just came out there can still be much info inferred as these are directly comparable to the toyo trampio 888s. the tread patter on these guys is sick, huge outter contact patches. early testing of these tires turned up lackluster, but the tire has been very well accepted by the community which may suggest that tire shaving could be crucial for this tire. the nt01 is also more heat forgiving and will work in a wider band of heat than most other r compound tires. definitely ASYMETRIC.
    comes in
    275 40 17
    245 40 18
    275 35 18

    MICHELIN PILOT SPORT CUP. these tires have mixed reviews but most likely because they need to operate very hot before maximum performance comes on. and after that fact they wear very well. these tires are favored by many porsche racers and will out grip just about all other treaded r compounds. ASYMETRIC tire can't be flipped.
    comes in
    245 40 17
    255 40 17
    275 40 17
    235 40 18
    265 35 18
    285 30 18

    YOKOHAMA ADVAN AO48, this is the replacement r comp from advan, i will not talk about the ao32 as it is discontinued. like all advans these are expensive. they come in varying degrees of hardness and for heavy cars like the evo you want the harder compounds. they will also not last very long and are not good for many seconds over ra1s however these new ones may pose a change. SYMETRIC can be flipped.
    comes in
    235 45 17
    245 40 17
    255 40 17
    235 40 18
    265 35 18

    KHUMO VICTORACER V700. these tires come with wee itty bitty tread depth. these tires will outperform ra1s in some aspects but the ra1 is generally more favored due to availability, standing the test of time with success and the fact that they last longer. that said the victoracer v700 will not last as long as the ra1 with street driving. ASYMETRIC not flippable. more info to come. khumo recommends tire shaving for all dry competition track use.
    comes in
    255 40 17
    275 40 17

    KHUMO ECSTA V700. these tires are great for autocross but not the best, more like an autocross practice tire. comes with itty bitty tread depth and will shave in quickly to slick. at autocross these tires will last many events. keep in mind that these do not compare to the victoracer v700 and are definitely not comparable in any way to the v710. khumo recommends tire shaving for all dry competition track use.
    comes in
    245 40 17
    275 40 17
    265 35 18
    305 30 18

    PIRELLI PZERO CORSA. tread pattern is worthless. warm up time is longer than that of an ra1 and it matters! these tires will not hook up well when cold but once warm they will dish out the status quo in terms of grip. these tires are also faily silent, they do not make very much noise when breaking away. these guys are ASYMETRIC and can't be flipped. i need info on how long these last at track days
    comes in
    235 45 17
    255 40 17
    255 35 18
    265 35 18
    285 30 18

    HANKOOK VENTUS Z211. total time attack tire. wears way too fast and takes a dump after more than two handfuls of heat cycles. but they're a lot faster than ra1s. they should basically be compared to a hoosier as they are about 1.5 seconds faster than ra1s. these are available in hard and soft compound. these tires are wider than most similar size description tires. ASYMETRIC
    comes in
    235 40 17 (thin)
    245 40 17
    255 40 17
    275 40 17
    265 35 18

    KHUMO ECSTA V710. autrocross and track tire, hoosier style 'slick' (two worthless thread lines). these tires whoop ass bascially and compete with hoosiers in autocross. at autocross people will tell you that these tires take all the heat and don't bat an eye, however i've still seen evo owners busting out the water sprayers between runs. when it's time for the ultimate performance at autocross this tire is run by everyone that is doing worthwhile times. ASYMETRIC. khumo recommends tire shaving for all dry competition track use.
    comes in
    275 40 17
    245 35 18
    285 30 18

    HANKOOK VENTUS Z214 this is a v710 like tire. and like the v710 it is a track only tire, two SYMETRIC lines for tread patter and steel belts. this is the slick type tire that was used by the xsengineering skyline for the american touge. this tire is likely the fastest tire in its class (belted tire with almost zero thread blocking), that said it doesn't last long and hardly anyone uses it. i regretfully cannot comment on the heat characteristics at this time. but thers is a c70 autocross specific compound.
    comes in
    275 40 17


    HOOSIER these are race tires. they will heat cycle out before dangerous wear shows and that said they'll wear quick too. hoosiers are notorious for being sensitive to heating and wearing, you gotta drive them right, smart, but when not asshatted all over the place there are few tires, sans slicks, that reward so directly. hoosiers have been known to wear on the shoulder, but new A6 and R6 tires have addressed that, how successfully is still yet to be determined.

    HOOSIER A6 this is the dot approved autocross tire, basically they have steel belts. since these are relatively new, little information is available. however basing off of the previous hoosier a-tire running them on a heavy evo may require attention to heat management.
    comes in
    245 40 17
    275 40 17
    245 35 18
    275 35 18
    285 30 18

    HOOSIER R6 this is the dot approved roadrace tire, basically they have steel belts.
    comes in
    245 40 17
    275 40 17
    245 35 18
    275 35 18
    285 30 18

    if you pay attention i've ordered all the tires in a 'most popular' or most likely to be picked kinda way, some of the most competitive tires won't be considered by many hence the hoosers and khumos roaring up the rear where the ra1s are very common for rcomps as they can be run on the street.

    i will not be duscussing slick tires as most people running slicks will not need this guide, that said most slicks are harder to find. just about every tire manufacturer makes slicks. yokohama, goodyear, michelin, hankook, dunlop, pirelli and bridgestone all make slicks. slicks are generally about 3 seconds faster than the fastest dot approved r compound tire of a similar size. slicks are very heat sensitive and very unforgiving to things such as tire lock up and too much slip angle. being a slick design the tire can shear easily and the wet performance is non existent. with that stated one can likely cheat by running a weather slick (a slick with thread pattern) and get most of the compound benefits while running in the dry. also slicks are weight sensitive as many of them are designed with a stripped race car in mind, so overheating is a problem which will increase the wear rate and the cycle life of the tire drastically.

  3. #3

    Re: the end all tire (and wheel) thread


  4. #4

    Re: the end all tire (and wheel) thread

    http://www.discounttiredirect.com/direct/brochure/info/tmpInfoWheelOffsets.jsp;jsessionid=GD1vyzyRdhZZT57 j219fKbhVw4TJzknJXJ4Jyp131QqShC2wnhhv!297449208!NO NE

    The offset of a wheel is what locates the tire and wheel assembly in relation to the suspension. More specifically, it is the measured distance between the hub mounting surface and the center line of the rim. Below is an explanation of the various types of offsets which are pictured in the above graphic.

    Positive Offset
    A positive offset occurs when the hub mounting surface is on the street side (the side you see) of the center line of the rim. Most factory rims will have this type of offset.

    Zero Offset
    When the hub mounting surface is centered within the rim, it is known as a zero offset.

    Negative Offset
    If the hub mounting surface is on the brake side of the center line of the rim, it is considered a negative offset or “deep dish”.

    * Note that extensive negative offset can potentially cause increased steering wheel kick-back and place additional stresses on the vehicle's entire suspension.

  5. #5

    Re: the end all tire (and wheel) thread

    http://www.tirerack.com/tires/tirete....jsp?techid=46

    The tire size branded on the sidewall provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability.

    Our primary example will be based on variations of the 225/50R16 size, although other sizes will appear where appropriate.

    Service Type
    Most tire sizes begin with a letter or letters that identify the type of vehicle and/or type of service for which they were designed. The common indicators are as follows:

    P225/50R16 91S

    P = When a tire size begins with a "P," it signifies the tire is a "P-metric" size that was designed to be fitted on vehicles that are primarily used as passenger vehicles. This includes cars, minivans, sport utility vehicles and light duty pickup trucks (typically 1/4- and 1/2-ton load capacity). The use of P-metric sizes began in the late 1970s and they are the most frequently used type of tire size today.

    225/50R16 92S

    If there isn't a letter preceding the three-digit numeric portion of a tire size, it signifies the tire is a "Metric" size (also called "Euro-metric" because these sizes originated in Europe). While Metric tire sizes are primarily used on European cars, they are also used on vans and sport utility vehicles. Euro-metric sizes are dimensionally equivalent to P-metric sizes, but typically differ subtly in load carrying capabilities.

    T125/90D16 98M

    T = If a tire size begins with a "T," it signifies the tire is a "Temporary Spare" ("space saver" or "mini spare") that was designed to be used temporarily only until a flat tire can be repaired or replaced.

    LT245/75R16 108/104S

    LT = If a tire size begins with "LT," it signifies the tire is a "Light Truck-metric" size that was designed to be used on vehicles that are capable of carrying heavy cargo or towing large trailers. This includes medium and heavy-duty (typically 3/4- and 1-ton load capacity) pickup trucks, sport utility vehicles and full-size vans. Tires branded with the "LT" designation are the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.

    7.50R16LT 112/107Q, 8.75R16.5LT 104/100Q or 31x10.50R15LT 109Q

    LT = If a tire ends with "LT," it signifies the tire is either an earlier "Numeric", "Wide Base" or "Flotation" Light Truck size designed to be used on vehicles that are capable of carrying heavy cargo and towing trailers (Numeric sizes), use 16.5-inch diameter rims (Wide Base sizes) or are wider, oversized tires designed to help the vehicle drive on top of loose dirt or sandy surfaces (Flotation sizes). This includes light, medium and heavy-duty (typically 1/2-, 3/4 and 1-ton load capacity) pickup trucks and sport utility vehicles. Tires branded with the "LT" at the end of their size designation are also the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.

    195/70R15C 104/102R

    C = If a Euro-metric sized tire ends with a "C," it signifies the tire is a "Commercial" tire intended to be used on vans or delivery trucks that are capable of carrying heavy loads. In addition to being branded with the "C" in their size, these tires are also branded with their appropriate Service Description and "Load Range" (Load Range B, Load Range C or Load Range D).

    ST225/75R15

    ST = If a tire size begins with "ST," it signifies the tire is a "Special Trailer Service" size that was designed to only be used on boat, car or utility trailers. ST-sized tires should never be used on cars, vans or light trucks.

    Section Width
    Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

    P225/50R16 91S

    The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width. Because many people think of measurements in inches, the 225mm can be converted to inches by dividing the section width in millimeters by 25.4 (the number of millimeters per inch).

    225mm / 25.4 = 8.86"

    Sidewall Aspect Ratio
    Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.

    P225/50R16 91S

    The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.

    Internal Construction
    A letter (R in this case) that identifies the tire's internal construction follows the two digits used to identify the aspect ratio.

    P225/50R16, P225/50ZR16

    The R in the P225/50R16 91S size identifies that the tire has a Radial construction in which the tire's body plies "radiate" out from the imaginary center of the wheel. Radial tires are by far the most popular type of tire today representing over 98% of all tires sold.

    If the R in the size was replaced with a D (225/50D16), it would identify that the internal tire body plies crisscross on a Diagonal and that the tire has a "bias ply" construction. Tires using this construction are for light truck and spare tire applications.

    If the R in the size was replaced with a B (225/50B16), it would identify that the tire body plies not only crisscross the tire on a diagonal as before, but that they are reinforced with belts under the tread area. This type of tire construction is called "Belted." Tires using this construction are practically extinct.

    Speed Rating
    Today, the only tires that continue to include the speed rating "in" the tire size (P225/50ZR16) are Z-speed rated tires. In this case, following the two digits used to identify the aspect ratio are the letters ZR to identify the tire's speed rating (Z) and its internal construction (R). Since 1991, all other speed ratings are identified in the tire's Service Description (which will be covered shortly).

    Tire and Wheel Diameter
    P225/50R16 91S

    The 16 indicates the tire and wheel diameter designed to be matched together.

    Tires that have a rim diameter expressed in inches (P225/50R16, as well as 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 24, 26 and 28) are called "inch rim" sizes, are the most common type of tire size and are used on most cars, minivans, vans, sport utility vehicles and light duty light trucks.

    While not as common, two additional "unique" types of tire/wheel diameters are still in use today.

    Tires and wheels that have a rim diameter expressed in "half" inches (8.00R16.5LT, as well as, 14.5, 15.5, 17.5 and 19.5) are used on some heavy-duty trailers, heavy-duty light trucks and box vans.

    Tires and wheels that have a rim diameter expressed in millimeters (190/65R390, as well as, 365 and 415) are called millimetric sizes. Michelin initiated millimetric sizes for their TRX tires that saw limited use on many different car models in the late 1970s and 1980s.

    Michelin PAX System run flat tires have been introduced as an integrated wheel/tire system on a very limited basis as Original Equipment (O.E.) in North America. An example PAX System size of 235/710R460A 104T expresses tire and wheel dimensions in millimeters (235 mm Section Width, tire Overall Diameter of 710 mm and a 460A mm rim diameter, with the "A" in 460A signifying these tires feature "asymmetric" beads in which the outside bead (450 mm) and inside bead (470 mm) are actually different diameters.

    All of these "unique" tire/wheel diameters were developed specifically because the tire and wheel design or intended vehicle use required them to be different than conventional tires and wheels. All of these tires and wheels feature bead profiles that have a different shape than traditional "inch rim" sizes.

    Tires and wheels with unique rim diameters should never be combined with traditional "inch rim" tires and wheels.

    It is critical that the tire and wheel diameters are always confirmed to match before the tire is mounted on the wheel.

    Service Description
    P225/50R16 91S

    The 91S represents the tire's Service Description. A Service Description identifies the tire's Load Index and Speed Rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991. For more information on Service Descriptions, click here http://www.tirerack.com/tires/tirete....jsp?techid=35.

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