Run slightly larger wall in rear? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

scottryan · 10-17-2018, 12:02 AM

Hey guys, so I'm currently running Enkei RPF1's 18x9.5 with 255/35/18 tires. My Coilovers are Yonaka Spec 2's (Camber adjustment), and I don't run slammed at all. I noticed recently how much room I have in my rear even with the 18" rim and was thinking of running a 265/40/18 on the back, would anyone be able to chime in and give some advice on running a 40 wall in the back with a 35 in the front? Major issues or just minor difference in the feel of the drive? The ride is raked towards the front the purpose of having room in the back.

Thank you in advance.

ZDan · 10-17-2018, 08:40 AM

Seems like a bad idea. You know 265/35-18 have more sidewall than 255/35-18, right? 255/35 front with 265/35 rear or 275/35-18 rears (a bit more sidewall still) would be a much better plan, I wouldn't even consider 265/40-18 which are more than an inch bigger in diameter vs 255/35

Leonardo · 10-17-2018, 10:37 AM

Quote:

Originally Posted by scottryan

Hey guys, so I'm currently running Enkei RPF1's 18x9.5 with 255/35/18 tires. My Coilovers are Yonaka Spec 2's (Camber adjustment), and I don't run slammed at all. I noticed recently how much room I have in my rear even with the 18" rim and was thinking of running a 265/40/18 on the back, would anyone be able to chime in and give some advice on running a 40 wall in the back with a 35 in the front? Major issues or just minor difference in the feel of the drive? The ride is raked towards the front the purpose of having room in the back.

Thank you in advance.

Don't do it. A 265/40/18 is too big of tire. As ZDan has already said, stick to 35 series, if you want to go taller and wider.

This thread has good info on page one about running 265 width.
http://www.ft86club.com/forums/showthread.php?t=41083

Stang70Fastback · 10-17-2018, 11:02 AM

That's a pretty large discrepancy front-to-rear. You're talking about a 20% taller sidewall, and a more than 5% increase in circumference, all for only a 4% increase in width.

Let's weigh the pros and cons.

Pros:

- *Slightly* more lateral grip (at the rear only.)
- Improved looks if you like a bit of rake.
- Improved ride comfort (at the rear only.)

Cons:

- Sloppier rear handling.
- Slightly increased propensity for understeer.
- Slightly less controllable rear end at the limit.
- Incorrect speedometer/odometer readings.
- Potential for ABS/TCS/ESC issues due to wheel speed sensor discrepancies.
- Slower acceleration.
- Slower top speed (at stock power levels, since our vehicles are drag limited.)
- Greater unsprung rear mass (I assume the 265 will be heavier.)
- More expensive tire (I assume it's more expensive.)
- Inability to rotate tires front-to-rear to maintain even wear.
- Inability to use spare tire for any length of time if you get a rear flat, seeing as the front tires (which are supposed to be rotated to the rear in the event of a flat) no longer match the rear tires.

Shark_Bait88 · 10-17-2018, 11:44 AM

Quote:

Originally Posted by scottryan

Hey guys, so I'm currently running Enkei RPF1's 18x9.5 with 255/35/18 tires. My Coilovers are Yonaka Spec 2's (Camber adjustment), and I don't run slammed at all. I noticed recently how much room I have in my rear even with the 18" rim and was thinking of running a 265/40/18 on the back, would anyone be able to chime in and give some advice on running a 40 wall in the back with a 35 in the front? Major issues or just minor difference in the feel of the drive? The ride is raked towards the front the purpose of having room in the back.

Thank you in advance.

Larger wheels don't fill out your wheel well anymore than smaller diameter wheels, because the difference in tire sidewall evens it out. 18" v 17" will end up with same overall diameter (roughly) when you include the tires.

Tcoat · 10-17-2018, 11:58 AM

Quote:

Originally Posted by Stang70Fastback

That's a pretty large discrepancy front-to-rear. You're talking about a 20% taller sidewall, and a more than 5% increase in circumference, all for only a 4% increase in width.

Let's weigh the pros and cons.

Pros:

- *Slightly* more lateral grip (at the rear only.)
- Improved looks if you like a bit of rake.
- Improved ride comfort (at the rear only.)

Cons:

- Sloppier rear handling.
- Slightly increased propensity for understeer.
- Slightly less controllable rear end at the limit.
- Incorrect speedometer/odometer readings.
- Potential for ABS/TCS/ESC issues due to wheel speed sensor discrepancies.
- Slower acceleration.
- Slower top speed (at stock power levels, since our vehicles are drag limited.)
- Greater unsprung rear mass (I assume the 265 will be heavier.)
- More expensive tire (I assume it's more expensive.)
- Inability to rotate tires front-to-rear to maintain even wear.
- Inability to use spare tire for any length of time if you get a rear flat, seeing as the front tires (which are supposed to be rotated to the rear in the event of a flat) no longer match the rear tires.

Your control systems will go insane and mess with you constantly!

tyler_win_photo · 10-17-2018, 12:35 PM

Definitely run a 35 series tire. 40 series with a 265 section is way too thick in terms of sidewall. And like others have noted, your TCS is not going to like it.

scottryan · 10-18-2018, 12:56 PM

Quote:

Originally Posted by ZDan

Seems like a bad idea. You know 265/35-18 have more sidewall than 255/35-18, right? 255/35 front with 265/35 rear or 275/35-18 rears (a bit more sidewall still) would be a much better plan, I wouldn't even consider 265/40-18 which are more than an inch bigger in diameter vs 255/35

Awesome response, this is why I always consult you guys. I didn't know the sidewall effectively changed from 255 to 265, I'll look into a rear 265, I really don't like the slightly stretched look with my current ones.

churchx · 10-18-2018, 03:32 PM

Sidewall height is given in "%" from width, not absolute values. So of course, wider tires with same procentual profile height will have also higher sidewall. While it is not that precise, simplest rule of thumb is when you up one of tire sizing, to keep diameter somewhat same, you lower other tire sizing parameter.
If one wishes for some weird tire choices, eg. for staggered setup (also not advised on these cars, but some go for such for sake of arguable looks and to fit max possible width tires, which is also not advisable), just google for tire calculator and use any of found online calculators to see how similar or dissimilar different sized tires will be.

10-17-2018, 12:02 AM	#1
scottryan Financial Distress Join Date: May 2018 Drives: 2017 GT86 325WHP Location: Ontario, Canada Posts: 142 Thanks: 89 Thanked 51 Times in 36 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	Run slightly larger wall in rear? Hey guys, so I'm currently running Enkei RPF1's 18x9.5 with 255/35/18 tires. My Coilovers are Yonaka Spec 2's (Camber adjustment), and I don't run slammed at all. I noticed recently how much room I have in my rear even with the 18" rim and was thinking of running a 265/40/18 on the back, would anyone be able to chime in and give some advice on running a 40 wall in the back with a 35 in the front? Major issues or just minor difference in the feel of the drive? The ride is raked towards the front the purpose of having room in the back. Thank you in advance.

10-17-2018, 11:02 AM	#4
Stang70Fastback A.K.A. Starlord Join Date: Oct 2013 Drives: 2015 Series.Blue Location: Illinois Posts: 1,842 Thanks: 845 Thanked 2,100 Times in 834 Posts Mentioned: 30 Post(s) Tagged: 3 Thread(s)	That's a pretty large discrepancy front-to-rear. You're talking about a 20% taller sidewall, and a more than 5% increase in circumference, all for only a 4% increase in width. Let's weigh the pros and cons. Pros: - Slightly more lateral grip (at the rear only.) - Improved looks if you like a bit of rake. - Improved ride comfort (at the rear only.) Cons: - Sloppier rear handling. - Slightly increased propensity for understeer. - Slightly less controllable rear end at the limit. - Incorrect speedometer/odometer readings. - Potential for ABS/TCS/ESC issues due to wheel speed sensor discrepancies. - Slower acceleration. - Slower top speed (at stock power levels, since our vehicles are drag limited.) - Greater unsprung rear mass (I assume the 265 will be heavier.) - More expensive tire (I assume it's more expensive.) - Inability to rotate tires front-to-rear to maintain even wear. - Inability to use spare tire for any length of time if you get a rear flat, seeing as the front tires (which are supposed to be rotated to the rear in the event of a flat) no longer match the rear tires. __________________ . Check out my blog, read all about my BRZ adventures, and oogle my sweet cell-phone photos! You can also find me on Instagram, and on Facebook.

10-17-2018, 12:35 PM	#7
tyler_win_photo Senior Member Join Date: Dec 2013 Drives: 2014 Scion FRS (Asphalt) Location: Redmond, WA Posts: 559 Thanks: 39 Thanked 173 Times in 143 Posts Mentioned: 6 Post(s) Tagged: 2 Thread(s)	Definitely run a 35 series tire. 40 series with a 265 section is way too thick in terms of sidewall. And like others have noted, your TCS is not going to like it. __________________ AVO Stage 2 Turbo Build Thread https://wheelwell.com/tyler-nguyen-1...014-scion-fr-s

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10-17-2018, 08:40 AM	#2
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,672 Thanks: 1,439 Thanked 4,012 Times in 2,098 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	Seems like a bad idea. You know 265/35-18 have more sidewall than 255/35-18, right? 255/35 front with 265/35 rear or 275/35-18 rears (a bit more sidewall still) would be a much better plan, I wouldn't even consider 265/40-18 which are more than an inch bigger in diameter vs 255/35

10-18-2018, 03:32 PM	#9
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,335 Thanks: 698 Thanked 2,086 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	Sidewall height is given in "%" from width, not absolute values. So of course, wider tires with same procentual profile height will have also higher sidewall. While it is not that precise, simplest rule of thumb is when you up one of tire sizing, to keep diameter somewhat same, you lower other tire sizing parameter. If one wishes for some weird tire choices, eg. for staggered setup (also not advised on these cars, but some go for such for sake of arguable looks and to fit max possible width tires, which is also not advisable), just google for tire calculator and use any of found online calculators to see how similar or dissimilar different sized tires will be.

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