18" Square Setup - Rotatable

[heyyouduh]

Originally Posted by aswy6

Already got 9.5 inch rim. I know 275 and 295 will fit on 9.5 and 10 inch rims but question is - should i go for it?

interestingly this article just became free to read for non GRM subscribers. Take a look. https://grassrootsmotorsports.com/ar...always-better/

[SYT_Shadow]

Originally Posted by heyyouduh

interestingly this article just became free to read for non GRM subscribers. Take a look. https://grassrootsmotorsports.com/ar...always-better/

Nothing surprising there.

The same tire will be faster in a wider wheel vs a narrower one, and you get to the point where a given wheel will not properly support wider tires and there isn't a point in just putting more tire on the wheel

[heyyouduh]

Originally Posted by SYT_Shadow

Nothing surprising there.

The same tire will be faster in a wider wheel vs a narrower one, and you get to the point where a given wheel will not properly support wider tires and there isn't a point in just putting more tire on the wheel

yes, motoiq had an article on this before as well.

that said, do you think a 295/30 is somewhat "wasted" on a 10.5 wheel? I ran 295/30 cup2s (TR lists tread width of 10.8", which suggest they belong on an 11" wheel) this past weekend which felt great, unfortunately no objective data due to other issues. Once these are gone will probably revert back to running 275/35 as they're slightly cheaper and pretty much every tire comes in that size.

[SYT_Shadow]

Originally Posted by heyyouduh

yes, motoiq had an article on this before as well.

that said, do you think a 295/30 is somewhat "wasted" on a 10.5 wheel? I ran 295/30 cup2s (TR lists tread width of 10.8", which suggest they belong on an 11" wheel) this past weekend which felt great, unfortunately no objective data due to other issues. Once these are gone will probably revert back to running 275/35 as they're slightly cheaper and pretty much every tire comes in that size.

I've run a ton of 295s on 10.5 wheels, I think that's the upper limit for most tires.

The only tire I've run in 295 where it seemed too wide for the 10.5" is the R888R in 295, which really needs an 11". Then again, that tire is a POS for track use so no issues there.
Toyo RR, BFG R1, Hoosier R7 etc all fit very well on 10.5 wheels at 295 width.

Fortunately, we don't have to get too scientific to know when tires are happy. OEMs like using wheels that are generally wider than the tires on them, leading to a 'stretched' look. All OEM M cars leave the factory with this setup.
You're fine with 'straight' sidewalls, and you know you're too wide when the wheel is pinching the tire and it looks too 'fat'

[aswy6]

Originally Posted by SYT_Shadow

I've run a ton of 295s on 10.5 wheels, I think that's the upper limit for most tires.

The only tire I've run in 295 where it seemed too wide for the 10.5" is the R888R in 295, which really needs an 11". Then again, that tire is a POS for track use so no issues there.
Toyo RR, BFG R1, Hoosier R7 etc all fit very well on 10.5 wheels at 295 width.

Fortunately, we don't have to get too scientific to know when tires are happy. OEMs like using wheels that are generally wider than the tires on them, leading to a 'stretched' look. All OEM M cars leave the factory with this setup.
You're fine with 'straight' sidewalls, and you know you're too wide when the wheel is pinching the tire and it looks too 'fat'

Thats a good info but my wheel is 10 inch wide in the back and im wondering if its okay to put 295 RE-71RS on there

[SYT_Shadow]

Originally Posted by aswy6

Thats a good info but my wheel is 10 inch wide in the back and im wondering if its okay to put 295 RE-71RS on there

I don't think itll be better than a 275 on the same wheel, but it's also not the end of the world

[heyyouduh]

Originally Posted by aswy6

Thats a good info but my wheel is 10 inch wide in the back and im wondering if its okay to put 295 RE-71RS on there

It will be okay as in it will be safe, but it won't be ideal from a performance standpoint. Read the link I posted above.

[aswy6]

Originally Posted by heyyouduh

It will be okay as in it will be safe, but it won't be ideal from a performance standpoint. Read the link I posted above.

Yeah i think all i care about is it being safe. Prob still going to be faster that 285s

[aswy6]

Originally Posted by SYT_Shadow

I don't think itll be better than a 275 on the same wheel, but it's also not the end of the world

Very interesting… not any faster?

[heyyouduh]

Originally Posted by aswy6

Yeah i think all i care about is it being safe. Prob still going to be faster that 285s

I really think you should read the GRM link above. It's a quick read. If you find yourself with more time read this:
https://motoiq.com/how-to-properly-select-and-size-tires-for-performance/

[aswy6]

Originally Posted by heyyouduh

I really think you should read the GRM link above. It's a quick read. If you find yourself with more time read this:
https://motoiq.com/how-to-properly-select-and-size-tires-for-performance/

Gave this a read… man running 275 in the back hurts my ego haha. Well last day i was running 265-285 RE-71R on stock rims. This time i bought wheels from someone and those have brand new R888R but 255-275 on 9.5 front and 10 rear rim. I was mostly eying 295 because RE-71RS dont come in 285

[heyyouduh]

Originally Posted by aswy6

Gave this a read… man running 275 in the back hurts my ego haha. Well last day i was running 265-285 RE-71R on stock rims. This time i bought wheels from someone and those have brand new R888R but 255-275 on 9.5 front and 10 rear rim. I was mostly eying 295 because RE-71RS dont come in 285

if it makes you feel better the 200tw category tires tend to run wide... a nominal 275 re71rs might be wider than a "regular" 275.

too bad there isn't more 295/35/18 or 305/35/18 in the 200tw category that has a corresponding front tire, if there were you may see more ppl running staggered

[RugbyBro]

Originally Posted by aswy6

Gave this a read… man running 275 in the back hurts my ego haha. Well last day i was running 265-285 RE-71R on stock rims. This time i bought wheels from someone and those have brand new R888R but 255-275 on 9.5 front and 10 rear rim. I was mostly eying 295 because RE-71RS dont come in 285

Check the tread width of the tires you're looking at. Stated width is usually a reference point, but many tires give you more (or sometimes less) than what is stated. Here's an example - The G8X * 275 front tires have LESS tread width than a 265 ECS02. So really those G8X * 275s are more like 265s.

Plenty of tires that may be 275 in name but really are wider (AO52s, CR-S, etc.)

[Theruleslawyer]

Originally Posted by aswy6

Gave this a read… man running 275 in the back hurts my ego haha. Well last day i was running 265-285 RE-71R on stock rims. This time i bought wheels from someone and those have brand new R888R but 255-275 on 9.5 front and 10 rear rim. I was mostly eying 295 because RE-71RS dont come in 285

I just got re71rs in 275/295 stagger. First race this weekend on them 10and11x18 wheels. They are pretty wide for the rated size. Wider than my rs4 were in the same size.

[E92inSG]

Originally Posted by Theruleslawyer

I just got re71rs in 275/295 stagger. First race this weekend on them 10and11x18 wheels. They are pretty wide for the rated size. Wider than my rs4 were in the same size.

those size tyres in those rim widths should be perfectly mounted for track usage. I have been using that exact setup. But will be moving to 295 square shortly.

[heyyouduh]

Originally Posted by Theruleslawyer

I just got re71rs in 275/295 stagger. First race this weekend on them 10and11x18 wheels. They are pretty wide for the rated size. Wider than my rs4 were in the same size.

let us know how it goes and how it compares to previous set up.

[FaRKle!]

Originally Posted by RugbyBro

Here's an example - The G8X * 275 front tires have LESS tread width than a 265 ECS02. So really those G8X * 275s are more like 265s.

BMW deliberately makes their star spec tires with more narrow tread widths so the sidewalls are preloaded for less flex and the tires are more responsive.

[RugbyBro]

Originally Posted by FaRKle!

BMW deliberately makes their star spec tires with more narrow tread widths so the sidewalls are preloaded for less flex and the tires are more responsive.

I don't doubt there's a reason they do it, the point of my post is that stated sizes don't always tell the full story.

[heyyouduh]

https://www.tirerack.com/tires/tests...y.jsp?ttid=296

"So what did we learn? The key takeaways are that in the dry, a wider tire does not automatically mean faster lap times. Using a wheel width that properly supports the tire will provide faster laps than a wider tire with very little wheel support. We saw this in our testing - the 215/45R17 tire on the 9" wide wheel was noticeably faster than the much wider 245/40R17 tire on the 7" wide wheel. That's not to say tire width doesn't matter, though, as the 225/45R17 combinations were all faster than the 215/45R17s. The 245/40R17 on the 9" wide wheel was very close to the 225/45R17 on the same wheel. If we could fit a 10" wheel width on our test cars, the pattern seems to indicate a 245 on a 10" would have been the fastest combination of all.

In the wet, a narrower tire is generally faster than a wide one, and once again, more support from the wheel is better. The 215s on the 8s and 215s on the 9s were the fastest combinations in the wet. The 215s on 7s, 225s on 8s, and 225s on 9s were a step back from there, and all the 245s, along with the 225s on 7s, set the slowest wet laps of the test."

I guess the days of cramming the biggest tire to a particular wheel are coming to an end.

iirc porsche also puts a relative "stretch" on their tires/wheels for the gt3.

[fanatic1]

Good to see this thread still active, think I bought these wheels 10.5 and tires 305 DH (run small) in the original post from Bracer.

991.1 GT3 comes with 245s on the front 9” wheels and 305 on the rear with 12” wheels. RS version adds 1/2” and slightly bigger tires.

[heyyouduh]

Originally Posted by Theruleslawyer

I just got re71rs in 275/295 stagger. First race this weekend on them 10and11x18 wheels. They are pretty wide for the rated size. Wider than my rs4 were in the same size.

Any updates? Esp any comparisons to other set ups thx

[Theruleslawyer]

Originally Posted by heyyouduh

Any updates? Esp any comparisons to other set ups thx

wcbmw ax3
https://youtu.be/XdiBPDJ39TU

So side wall is softer than the rs4. Makes they feel a little squishy. Ultimate grip is way up. I'd say it like turn in on trail braking and ultimate balance it pretty good. Try and turn in without setting the weight transfer and they would push a bit. Powering out of corners it feels right.