Hey guys,

After years of testing and compiling data, I finally condensed everything I have learned down into one article on How to PROPERLY select and size TIRES for PERFORMANCE.


This article disproves a lot of common misconceptions (actually, almost every aspect of the tire from the UTQG and temperature to the labeled width of the tire) and challenges the typical thought process of how people look for new tires and gives a better alternative that will make sizing wheels and tires much easier in the future with less trial and error. The information here applies both for street cars as well as dedicated track cars.


"The most important part of your car is not the engine, suspension, or brakes. It’s the TIRES!!! This is because your car can only perform as well as the capability of its tires. I’m often asked which tire is best and what size to buy. In this article I discuss my methods for choosing and properly sizing the right tires. I’m not into the “hella-flush” or “stance” scenes so this article is focused towards those who care about the PERFORMANCE of their car, whether on the street or on the track."

http://www.motoiq.com/MagazineArticl...RFORMANCE.aspx




Enjoy!

 

Great article

According to your article the ever popular 255 tire on a 9in wheel is not ideal. Most of the 245/40/17 performance tires on Tirerack seem to have 8.5-9.1in tread widths which is ideal (per your article) for a 9in wheel.

Why does everyone seem to run 255s?

 

How did you draw that conclusion? It does not seem to follow my "rule of thumb" on the top of page 3.

And WHAT tire are you referring to (since the written width is somewhat irrelevant)?

 

Good contribution Hope this will be viewed and help a lot of folks in here and save me a little breath to boot. Just to reiterate on one of the bigger points(and there were several)Selecting the tire and THEN the wheels is the way it should be done, but so often is not, and this is shown time and time again with the post in this forum. Id say about half in here are for show and don’t care, and a sizable portion of the other half do care about performance but haven’t made connection yet on how to acquire it effectively.

Also I do see some percentage of folks bleed over from some track and auto X or people that follow their spec, however don’t realize that many of these are class based limited set ups and are compromised, such as very wide tires for too narrow of a rim, and then gets confused with the best set up for everything vs just what’s the best compromise for a particular class based car.

 

A popular setup on the S2000 as of late is a 255/40 on a 17x9 (17x9 being popular due to having wheel model options and fitting under the stock wheel wells, vs most 17x9.5 and 17x10 wheels not coming in proper offsets). The tread width of the popular 255/40 tires mounted on 17x9 are, for example,

Dunlop ZII SS - 10"
RE71R - 9.6"
RS3v2 - 9.6"

So this goes against your article. The question posed was; Why do so many people run this setup, which is ~1"(or more) wider than your suggestion of .5" less than the wheel width?

 

I may have totally misunderstood something but this is what I'm talking about:

Tread widths per Tire Rack:
245/40r17 ZII Star Spec: 9.2in
255/40r17 ZII Star Spec: 10in

245/40r17 POTENZA RE-71R: 8.6in
255/40r17 POTENZA RE-71R: 9.6in

245/40r17 R-S3 V2: 9.1in
255/40r17 R-S3 V2: 9.6in

“For ideal handling: when sizing a tire for a given wheel, I usually target a tire’s TREAD width to be as wide as the WHEEL width, or 0.5” narrower than the wheel width.”

The popular setup I've seen on here involves 9in wide wheels with 255 tires. I selected the 3 above because they seem to be fairly common or well liked around here. I was shopping for a set of auto-x wheels and tires last night and noticed that all of the 255/40r17 tires I looked at had a tread width about a half inch wider than a 9in wheel while most 245 series tires had tread widths anywhere from .5in under the wheel width too slightly over (like the Star Specs and R-S3s).

Your rule of thumb states that the ideal tire for a 9in wheel would have a tread width between 8.5 and 9 inches correct?

EDIT: Sniped by AE_Racer

This kind of answers my question actually:
It's a compromised setup to try to squeeze as much tire as possible under the stock fenders while staying within class restrictions for auto-x (STR?). I assume there has to be some performance benefit of that setup over 245's all around or else people wouldn't be doing it in the name of competition.

 

Read the article.

But here is a general rule I go by for 17" extreme summer tires with proper rim to tire width for maximum tire grip and handling.

8"/215
9"/225
9.5"/245
10"/255
11"/275
11.5"/295
12"/315

....

As what was mentioned in the article the tire manufacture have some variant in specs on width, but as a general rule this is what you aim for, give or take .5". For my personal S2k, I run a 255/295 Kuhmo XS and a 10/11.5" wheel allows the absolute best tire profile for the best traction and handling precision on these tires widths. A 255 on a 9" wheel is totally acceptable and common, but it isnt the absolute best performing. Wheel widths and offset availability for the s2k is the bigger obstacle that interferes with this.

 

I think you answered your own question:

 

Lol, I guess more people like to just cruise or hardpark their cars vs driving it spiritedly. It blows my mind when I look at a set of nice used wheels and they are shod with Linglong, WanLi, Nankang or whatever crap tires they decided to cheap out with.

 

Tires are paramount but Show sells more wheels and tires than Go I imagine.

Extreme performance summer tires have advanced to the point we don't need them off the Autocross track and they've given up roadability for performance few of us can challenge. I know in my own case the loss of the Bridgestone RE-11A tires will probably require me to drop out of the Extreme Performance level when they need replacement. The current Max performance tires are better than the Extremes from a few years ago.

I won't put up with the horrible road noise of the current generation extreme performance summer tires for that 0.01 second advantage at performance levels I've yet to achieve. Yeah, some professional race driver in a prepared car ran around some Japanese race track faster on the RE-71R tires than last year's RE-11As. Only a scant few of us will match those times no matter what tires are on the car.

I truly believe excellent tires are the best choice for enjoying this car as a performance car. I also believe in the laws of diminishing returns and "good enough." Most guy use tires that are good enough for them.

-- Chuck