jaimesix

My RX8 is lowered with OHLINS suspensión and racing beat away bars

Drives nice

Using 245/40/18 My tires are about done

Looking for some 255/40/18

Anyone using this size on the stock wheels ?

Any photos would be appreciated

👍

DannyR3

I wouldn't go to a taller radius tire and cripple the anemic acceleration even more. Since you're on coilovers I'd step down to a 35 sidewall. The 255 will fit fine. I have 255 width Continental extremecontact sports on my R3 wheels.

jaimesix

Hi
Thanks for your reply The size comparison between the stock tire size 225-45-18 and this other size 255-40-18 are very similar

Same aspect ratio and diameter Only a tad wider

The size I currently have , 245-40-18 is a tad smaller in aspect ratio and diameter

So the 255-40s would add width to stock dimensions

This 255-40s would add size to the “current size 245-40s”

The 255-35s tires are smaller in diameter and aspect ratio than both stock size 225-45 and current 245-40 That is my concern with the 255-35 versus the 255-40


Size comparison Stock size 225-45 versus 255-40 Very similar except width

225-45 stock versus 255-40

Current size on car now, 245-40 versus 255-35 the 255-35 is wider but smaller in diameter

Visible reduction in diameter

DannyR3

Yeah I was off. My R3 wheels are 19 inch instead of 18 inch and I was thinking of the sidewall height for that lol. My tires are 255/35/19 so that's where I tripped up. 255/40/18 should work fine.

Steve Dallas

EDIT:

The forum somehow ate my original post. The gist of it was:

1. The rim width determines tread width more than tire section width
2. A 255 tire on an 8" rim will be maybe 1/4" wider than a 225 where it matters
4. A 255 tire weighs more and increases rotational mass
5. A 255 tire will have more sidewall flex and will roll and "squirm"
6. A 255 tire costs more than a 225 tire
7. A 255 tire does offer some protection against curb rash

Go narrower.

A 225 tire mounted on a 9" rim (in my living room). Tread width is 8 5/8":




A 255 tire mounted on a 9" rim (in my garage). Tread width is 8 3/4":




Courtesy of Flyin' Miata:

jaimesix

Thanks Steve

I ordered 245’ s last week through COSTCO

Will get them installed this weekend

I realized the benefit of using 255’s could only be enjoyed using wider wheels

So will study the wheel situation and will look for light wheels that are wider and later on in my next change will take the leap

perhaps 18X10 Wonder how the 245’s would adapt to a 10 in wheel or a 9. Stock is 8 as we know

Have to study the wheel backspacing measures I like the most possible portion inside the car

So far I ordered size 245/40/18 as I have now

I think this 245 is the ideal size for the 8 wheel And the 245 protects the wheel With the stock size 225-45 I messed my front wheel once

👍

Steve Dallas

Your 245s will fit on a 9 or 9.5" rim with no problem.

I run 225s on 9" rims on my Miata track car and have for 3 years now. It is a very common configuration in the SuperMiata world, and it provides a ton of grip for that little car.

My E46 is set up with 255s on 10.5" rims. This is also a common configuration for time attack and also works very well.