best size for new tires
 

Hey guys, so i'm currently on the 17x7.5 pp wheels and i will be going to a 18x8 summer set up. im looking at the wheel it fit calculator and wanted to know if there is a benefit or effects between going 225-45r18 vs 235-40r18?

You want 225/40-18, nearly stock diameter. 225/45-18 is an inch too tall...

235/40-18 is a bit tall as well (+0.7") and IMO 235 wants an 8.5" wheel width anyway.

Second vote for 225/40

its what im running on the stock tS's 18x8 and its the proper size and height and price. anything more than 225 is too much tire for an NA car anyhow

If you want to keep the diameter of the tire as close to the factory spec as possible, then I would recommend that you get 235/35/18.

235/35/18 would be 0.6% smaller in diameter than the OEM Michelin Primacy's, and a 235/40 would be 3% larger in diameter than the factory tires.

-Sam

best size for new tires
 

A 235/35R18 would be the closest in terms of diameter, however isn't a super common size compared to the 225/40 (limiting tire choice). Being that your next set will be 8" wide; the 235 may be a little on the wide side.



A 225/40R18 is the correct width for an 8" wheel, and the added sidewall height will only help counter the increased harshness by going up in wheel diameter.



We run 245/40R17's on our shop BRZ, which is actually even larger in diameter. :)

Edit: 245/40R17 and 215/45R17 are within a few millimeters in diameter.

it looks like im going to go with 225/40r18. thanks guys

Lmao! 235/35/18! That is a super rare size that is stupid expensive!

225/40/18 is the CORRECT size.

225. There are just sooo many more choices and 225's are plenty for this car with stock power.

Am I being lied to? 245/40/17 is very close to factory 215/45/17.. No?

Source: https://tiresize.com/calculator/

best size for new tires
 

Oops! Yes, you’re correct. They’re very close. I was thinking of another tire combo for some reason. Factory AP2 s2000’s actually run a 215/45 front, 245/40 rear. They’re within 3 millimeters in diameter.

That being said, my statement stays the same regarding recommendation. 225/40R18 would be the way to go for an 18x8 on a BRZ.