best size for new tires - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

deku · 06-06-2019, 05:51 PM

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?

ZDan · 06-06-2019, 05:59 PM

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.

Clutch Dog · 06-06-2019, 07:11 PM

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

eastendraceshop · 06-06-2019, 07:17 PM

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

WORKS · 06-06-2019, 07:46 PM

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.

deku · 06-07-2019, 09:41 AM

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

Leonardo · 06-07-2019, 10:47 AM

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

225/40/18 is the CORRECT size.

TommyW · 06-07-2019, 10:56 AM

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

Jordanwolf · 06-07-2019, 10:59 AM

Quote:

Originally Posted by WORKS

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.

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

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

WORKS · 06-07-2019, 11:05 AM

Quote:

Originally Posted by Jordanwolf

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

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

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.

06-06-2019, 07:46 PM	#5
WORKS Join Date: Feb 2014 Drives: WORKS CARB Legal Turbo BRZ Location: Sonoma Raceway - Bay Area Posts: 980 Thanks: 407 Thanked 646 Times in 350 Posts Mentioned: 31 Post(s) Tagged: 2 Thread(s)	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. __________________ Last edited by WORKS; 06-07-2019 at 11:11 AM.

06-07-2019, 10:47 AM	#7
Leonardo Country Boy 4 Life Join Date: Jul 2012 Drives: 19' & 06' Ridgelines, 13' FR-S Location: EUGENE Posts: 5,228 Thanks: 6,719 Thanked 5,291 Times in 2,720 Posts Mentioned: 47 Post(s) Tagged: 1 Thread(s)	Lmao! 235/35/18! That is a super rare size that is stupid expensive! 225/40/18 is the CORRECT size. __________________ I LIKE TIRES!

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06-06-2019, 05:59 PM	#2
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,584 Thanks: 1,376 Thanked 3,890 Times in 2,032 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	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.

06-06-2019, 07:11 PM	#3
Clutch Dog Senior Member Join Date: Jan 2019 Drives: 2017 BRZ PP , 2005 Saab 97X Location: CA Posts: 1,052 Thanks: 754 Thanked 721 Times in 405 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	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

06-06-2019, 07:17 PM	#4
eastendraceshop Senior Member Join Date: Oct 2018 Drives: '13 Scion FR-S & '17 Toyota 86 Location: Chino, CA Posts: 798 Thanks: 406 Thanked 228 Times in 165 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	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

06-07-2019, 10:56 AM	#8
TommyW Senior Member Join Date: Feb 2017 Drives: '13 Whiteout Location: San Clemente Posts: 1,491 Thanks: 496 Thanked 1,242 Times in 673 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	225. There are just sooo many more choices and 225's are plenty for this car with stock power.

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