Tire and Wheel Combination | Video

[Swolzee]

Surprisingly good video from Tire Rack, featuring a 2022 BRZ.

[Kulebrero]

Originally Posted by Swolzee

Surprisingly good video from Tire Rack, featuring a 2022 BRZ.

Nice video indeed. And interesting findings.

I’m running 245s on a 9” wheel. Been thinking about getting a second set of wheels/tires. Might give 9.5” with 245s a try. And when it comes time to replace the tires on the 9”, I might go with 225s to see how they feel.

Question is, should I stick with 17” or move up to 18”?

Been having brake issues. Just upgraded to 325mm BBK, but might have to move up to 340+mm which would require 18” wheels.

Decisions.

[cmiovino]

Originally Posted by Kulebrero

I might go with 225s to see how they feel.

Question is, should I stick with 17” or move up to 18”?

You have to keep other things in mind. 17" offers enough sidewall that the tire isn't going to feel sloppy like a 16" with a 55 series sidewall, but the 18" is going to start adding more weight to the wheel. Generally the crossoverpoint in terms of weight in 17-18 inches in tire because 18" tires sometimes have more or the same weight as 17", but the 18" wheel can be heavier than 17.

In general, track guys looking for weight savings generally stick to 17".

Tire sizing with width, given the wheel is wide enough, the 245 is going to be faster. Remember that the course this is being tested on is more of an autocross style course. I'd still prefer 245's for autocross. It would really be coming down to the feel of the tire making the driver's faster and pushing more. I'd still edge that given the actual lap times are so close between 225 and 245 on the 9", 245 is probably going to come out on top at a larger circut style track.

245 is the go-to for STX on a 9" wheel for these cars, tried and tested over years. No one is running a 225 on 9" because it magically is faster.

Originally Posted by Kulebrero

I might go with 225s to see how they feel.
Been having brake issues. Just upgraded to 325mm BBK, but might have to move up to 340+mm which would require 18” wheels.

Decisions.

Originally Posted by Kulebrero

Been having brake issues. Just upgraded to 325mm BBK, but might have to move up to 340+mm which would require 18” wheels.

The brake issue doesn't make a lot of sense to me. Generally any BBK is going to get the job done for 95%+ of people. Going from a 325 to 340mm, you better be absolutely pushing the extreme limits of the 325, going for all out lap times in a damn near race car.

Point is, any braking issues you're seeing on a light BRZ aren't going to be fixed increasing brake size like this. It's probably more pad related or perhaps even tire related. I don't think this is necessary at all, especially for the cost.

[Kulebrero]

Originally Posted by cmiovino

You have to keep other things in mind. 17" offers enough sidewall that the tire isn't going to feel sloppy like a 16" with a 55 series sidewall, but the 18" is going to start adding more weight to the wheel. Generally the crossoverpoint in terms of weight in 17-18 inches in tire because 18" tires sometimes have more or the same weight as 17", but the 18" wheel can be heavier than 17.

In general, track guys looking for weight savings generally stick to 17".

Tire sizing with width, given the wheel is wide enough, the 245 is going to be faster. Remember that the course this is being tested on is more of an autocross style course. I'd still prefer 245's for autocross. It would really be coming down to the feel of the tire making the driver's faster and pushing more. I'd still edge that given the actual lap times are so close between 225 and 245 on the 9", 245 is probably going to come out on top at a larger circut style track.

245 is the go-to for STX on a 9" wheel for these cars, tried and tested over years. No one is running a 225 on 9" because it magically is faster.





The brake issue doesn't make a lot of sense to me. Generally any BBK is going to get the job done for 95%+ of people. Going from a 325 to 340mm, you better be absolutely pushing the extreme limits of the 325, going for all out lap times in a damn near race car.

Point is, any braking issues you're seeing on a light BRZ aren't going to be fixed increasing brake size like this. It's probably more pad related or perhaps even tire related. I don't think this is necessary at all, especially for the cost.

I’m running 245s on 17x9 because it’s what a good amount of people are doing and it works well, but it doesn’t mean the case is closed and done. I ran 225 on 17x9 on my Miata, but never had the chance to compare it with 245s. Since I’m thinking of getting a second set, I’d might as well give it a try.

[Pat]

Originally Posted by cmiovino

Going from a 325 to 340mm, you better be absolutely pushing the extreme limits of the 325, going for all out lap times in a damn near race car.

For the most part I agree with what you say. I will add one other little tidbit though. I was using the AP Sprint kit with DTC-60s on my ZD6. I would heat check the front rotors to the point they needed to be replaced in one season of driving. The rotor thickness was still near new. On my new ZD8 I decided to go with a 355 mm rotor to hopefully decrease long-term running costs through lower breaking system heat. My powertrain is stock on my new car just as it was on my old car.

(I had beers with your old autocross buddy Kyle a couple weeks ago. Seeing him at the NASA event this weekend too. )

[strat61caster]

265 on 18’s trophied last year and is likely a contender to win.

245/40/17 on 17x9 is lemming effect, not proven imho, but because nobody has been playing around us lemmings are safe to stick to what we know. Tire racks test has me interested in trying 225 on a 9 but it’ll probably be post nats for me.

[Spuds]

I'm in the situation of picking tires for 9" wheels right now and this sizing question is throwing more variables into the mix. And then I wonder how a 235/40 or 45 would do.

[cmiovino]

Had an interesting data point that matches their results at our autocross event.

I run a 225/45/17 in DS on a first gen. The idea is to run the stock wheels because once I go STX, I'll get wheels then. Most others guys with gen 2's are running 245's, different offsets, etc. We have about 5+ gen 2's running all the time.

It rained and on 225's I was ahead of all of them by a large margin. I guess there's some truth in TR's results that running a ~225 in the wet might be more beneficial than cramming a 245 on a 7.5". I still think in the dry a 245 is better. They all creamed me once it dried up.

[Spuds]

Another interesting bit about the tires they tested. The 225s are have an "XL" load category and are rated for more weight than the 245s, which are "SL". Not sure what that actually means in terms of tire structure, but that might have something to do with the results.

[NoHaveMSG]

Originally Posted by strat61caster

245/40/17 on 17x9 is lemming effect, not proven imho, but because nobody has been playing around us lemmings are safe to stick to what we know. Tire racks test has me interested in trying 225 on a 9 but it’ll probably be post nats for me.

I sorta agree, I think a good amount of it is also specific to a tires particular characteristic. 245/40 seems to be a pretty safe choice in all brands. I have ran 235 in the Z3 and SX2 and liked them in that size. Also keeping in mind that not all tires measure out the same to what is printed on the sidewall.

[cjd]

Originally Posted by strat61caster

265 on 18’s trophied last year and is likely a contender to win.

245/40/17 on 17x9 is lemming effect, not proven imho, but because nobody has been playing around us lemmings are safe to stick to what we know. Tire racks test has me interested in trying 225 on a 9 but it’ll probably be post nats for me.

That was with the shorter gearing of a 17+ no? I run 255 for that reason...

[Kulebrero]

Originally Posted by strat61caster

265 on 18’s trophied last year and is likely a contender to win.

245/40/17 on 17x9 is lemming effect, not proven imho, but because nobody has been playing around us lemmings are safe to stick to what we know. Tire racks test has me interested in trying 225 on a 9 but it’ll probably be post nats for me.

Agreed.

A lot of what people recommend and do is based on anecdotal evidence. 245s on 9s appear to be a very good combo and may actually be the optimal tire/wheel setup, but unless we have objective studies similar to the TR test, it’s hard to say which one is the best combo for sure.

The TR test shouldn’t be accepted as canon, but it at least warrants consideration. I don’t think it is conclusive that 245 on 9 is the best option for track/autocross duty. It also isn’t a bad combo.

Btw, the TR test wasn’t about the best combo for a GR86. It was just about the best tire and wheel width combo for 225s and 245s. It is possible our cars do even better with 265s on something else. It’d be sweet to have TR’s resources and do tests all day to figure out the best option for the 86/BRZ.

[ruturaj001]

Originally Posted by Spuds

Another interesting bit about the tires they tested. The 225s are have an "XL" load category and are rated for more weight than the 245s, which are "SL". Not sure what that actually means in terms of tire structure, but that might have something to do with the results.

This is what I found on bob is the oil guy forum, I am quoting a member here but interesting answer

Some tire manufactures offer the same tire model in a Standard Load and an XL version. The XL version might have a 2 ply sidewall while the Standard Load version may have a 1 ply sidewall. You might get a better ride with the 1 ply sidewall while the 2 ply version could provide better steering response.