effects of bigger wheels-video - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Mitch · 07-01-2012, 01:38 AM

I wish they had just gone wider instead of going to a larger wheel at the same time. Would have been much more useful information. Still a very good demonstration.

Agnostik · 07-01-2012, 03:08 AM

Quote:

Originally Posted by Mitch

I wish they had just gone wider instead of going to a larger wheel at the same time. Would have been much more useful information. Still a very good demonstration.

Out of curiosity, what would one expect the outcome to be had they stayed with 17 diameter, but wider tires?

Been looking to go with 17x8 wrapped in 245/40 and curious whether I will see as much of an improvement over staying closer to the stock width just better tire.

Mitch · 07-01-2012, 03:27 AM

Quote:

Originally Posted by Agnostik

Out of curiosity, what would one expect the outcome to be had they stayed with 17 diameter, but wider tires?

Been looking to go with 17x8 wrapped in 245/40 and curious whether I will see as much of an improvement over staying closer to the stock width just better tire.

More weight could slow the car down, more surface area could help deal with imperfections in the track surface and maybe even keep the tires incrementally cooler. Not really sure, that's why I would have wanted to see that. I've been looking at 17x8 245/40/17 as well (RPF1s and Star Specs).

ZDan · 07-01-2012, 08:00 AM

Ideally they would have tested StarSpecs in OEM size, then same-diameter 245/40-17, and maybe after that, same-diameter 245/35-18. The 235/40-18 test tells us nothing due to the gearing change. I also hate +1 tests where they increase tire width for the larger-diameter wheel setup. If performance improves, was it due to the greater width or larger wheel diameter/shorter sidewall?! You have to separate the two changes out in order to be able to draw conclusions.

Anyway, I think it's easy to overestimate the benefits of going wider, particularly for a modest power/weight car. At Watkins Glen, I was <1 second slower on 205/225 street tires vs. wider 225/245 R-comps in the S. And surely *some* of that was due to R-comps (although they were Kumho VictoRacers, not the grippiest Rs, vs. Dunlop SportMaxx TT front and StarSpec rear street tires).

For sure, getting the right tire is far more important than width. Stock-size StarSpecs were 2.3 seconds faster than the OEM tires in this test, but I wouldn't expect 245/40s StarSpecs to be more than another couple of tenths quicker, if that.

As for going to larger-diameter wheels, I don't see anything but negatives. No reason a 245/35-18 tire should outhandle a 245/40-17 tire of the same make/model (given that it's a serious performance tire), and the 18" setup will generally have greater polar moment of inertia (resistance to spinning up) and will always be more expensive.

Dave-ROR · 07-01-2012, 09:50 AM

Merged a repost in here.

07-01-2012, 08:00 AM	#18
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)	Ideally they would have tested StarSpecs in OEM size, then same-diameter 245/40-17, and maybe after that, same-diameter 245/35-18. The 235/40-18 test tells us nothing due to the gearing change. I also hate +1 tests where they increase tire width for the larger-diameter wheel setup. If performance improves, was it due to the greater width or larger wheel diameter/shorter sidewall?! You have to separate the two changes out in order to be able to draw conclusions. Anyway, I think it's easy to overestimate the benefits of going wider, particularly for a modest power/weight car. At Watkins Glen, I was <1 second slower on 205/225 street tires vs. wider 225/245 R-comps in the S. And surely some of that was due to R-comps (although they were Kumho VictoRacers, not the grippiest Rs, vs. Dunlop SportMaxx TT front and StarSpec rear street tires). For sure, getting the right tire is far more important than width. Stock-size StarSpecs were 2.3 seconds faster than the OEM tires in this test, but I wouldn't expect 245/40s StarSpecs to be more than another couple of tenths quicker, if that. As for going to larger-diameter wheels, I don't see anything but negatives. No reason a 245/35-18 tire should outhandle a 245/40-17 tire of the same make/model (given that it's a serious performance tire), and the 18" setup will generally have greater polar moment of inertia (resistance to spinning up) and will always be more expensive. Last edited by ZDan; 07-01-2012 at 11:07 AM.

07-01-2012, 09:50 AM	#19
Dave-ROR Site Moderator Join Date: Dec 2010 Drives: Stuff Location: Florida Posts: 10,317 Thanks: 955 Thanked 5,965 Times in 2,689 Posts Mentioned: 262 Post(s) Tagged: 8 Thread(s)	Merged a repost in here. __________________ -Dave Track cars: 2013 Scion FRS, 1998 Acura Integra Type-R, 1993 Honda Civic Hatchback DD: 2005 Acura TSX Tow: 2022 F-450 Toys: 2001 Chevrolet Corvette Z06, 1993 Toyota MR2 Turbo, 1994 Toyota MR2 Turbo, 1991 Mitsubishi Galant VR-4 Parts: 2015 Subaru BRZ Limited, 2005 Acura TSX Projects: 2013 Subaru BRZ Limited track car build FS: 2004 GMC Sierra 2500 LT CCSB 8.1/Allison with 99k miles

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07-01-2012, 01:38 AM	#15
Mitch form follows function Join Date: Nov 2011 Drives: RIP '13 BRZ Location: Baton Rouge Posts: 688 Thanks: 42 Thanked 234 Times in 122 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	I wish they had just gone wider instead of going to a larger wheel at the same time. Would have been much more useful information. Still a very good demonstration.

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