225/45/15 vs 255/40/17 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Turbo Den · 06-26-2013, 05:19 PM

I am in STX.
I am facing a tough fight in my club's autox. Please help.

driving my wife's automatic FRS. I have Tein H-tech & Koni, rear control arm, front camber bolt. intake & cat-less front pipe. I don't want to spend more money on suspension or engine parts.

All else remains the same, how would you feel about:
255/40/17 vs 225/45/15 ???

BFG Rivals.
23" vs 25" diameter for better acceleration to compensate for longer gear ratio in automatic.
but 8.5" vs 9.5" treadwidth kinda counter-intuitive.

celica73 · 06-26-2013, 09:42 PM

top speed in 2nd with the 225/45-15?

Simmons · 06-26-2013, 09:59 PM

I have thought about doing this also, I just didn't want to invest in custom 15x9 wheels to find out.

Simmons

BlaineWasHere · 06-27-2013, 01:17 AM

Front sway bar?

mla163 · 06-27-2013, 08:18 AM

255/40/17 is too big. You'll lose acceleration

225/45/15 is too small. Like 10% less circumference. You may top out 2nd gear at 50 mph or so. It may work on a slow course. Even if it does, you may have brake fitment issues.

Turbo Den · 06-28-2013, 05:51 PM

with 255/40/17 ... accelerate earlier without spinning the rear.
at 225/45/15... accelerate faster, but probably later to avoid spinning the rear.

i have a 22mm whiteline front sway bar, softest setting.

feldy · 06-28-2013, 06:08 PM

I run a auto in stx as well. I have been through 4 sets of race tires since last year. I ran two sets of 225/45/17 last year. Not enough tire.

This year I ran at the start of the year toyo r1rs in a 245/35/17 these were amazing and I may get them next year. They helped acceleration a ton. You still hit 60 in 2nd and its only 23 pounds. My 245/40/17 rs3s are also great. But weigh more.

GTM_Challenge · 06-28-2013, 06:25 PM

Did the OP mean 225/45/17?

Turbo Den · 06-30-2013, 04:53 PM

Nope. 225/45/15 is correct. 15". We know 15" wheels will fit. Just a matter of tire size dilemma.

06-26-2013, 05:19 PM	#1
Turbo Den Member Join Date: Aug 2012 Drives: FRS, IS300, 911sc Location: Vancouver, BC Posts: 50 Thanks: 14 Thanked 12 Times in 7 Posts Mentioned: 0 Post(s)	225/45/15 vs 255/40/17 I am in STX. I am facing a tough fight in my club's autox. Please help. driving my wife's automatic FRS. I have Tein H-tech & Koni, rear control arm, front camber bolt. intake & cat-less front pipe. I don't want to spend more money on suspension or engine parts. All else remains the same, how would you feel about: 255/40/17 vs 225/45/15 ??? BFG Rivals. 23" vs 25" diameter for better acceleration to compensate for longer gear ratio in automatic. but 8.5" vs 9.5" treadwidth kinda counter-intuitive.

06-26-2013, 09:59 PM	#3
Simmons Senior Member Join Date: Jun 2012 Drives: 2024 GR86/ 2015 FRS Location: PA Posts: 961 Thanks: 306 Thanked 575 Times in 269 Posts Mentioned: 17 Post(s)	I have thought about doing this also, I just didn't want to invest in custom 15x9 wheels to find out. Simmons __________________ 2024 GR86 71 STR/ 2015 FRS 71 STX Sponsors Xero-Limit//Karcepts

06-27-2013, 01:17 AM	#4
BlaineWasHere Grip>Drift Join Date: Jun 2012 Drives: FRS Location: NorCal Posts: 3,472 Thanks: 782 Thanked 1,749 Times in 918 Posts Mentioned: 53 Post(s)	Front sway bar? __________________ My FR-S Build Thread!

06-28-2013, 06:08 PM	#7
feldy Senior Member Join Date: Aug 2011 Drives: 2013 FRS Asphalt Location: SF Bay Area Posts: 1,155 Thanks: 309 Thanked 335 Times in 212 Posts Mentioned: 21 Post(s)	I run a auto in stx as well. I have been through 4 sets of race tires since last year. I ran two sets of 225/45/17 last year. Not enough tire. This year I ran at the start of the year toyo r1rs in a 245/35/17 these were amazing and I may get them next year. They helped acceleration a ton. You still hit 60 in 2nd and its only 23 pounds. My 245/40/17 rs3s are also great. But weigh more. __________________ 2013 Scion FR-S AT Picked up 5/30/2012

06-26-2013, 09:42 PM	#2
celica73 Senior Member Join Date: Jun 2012 Drives: '13 BRZ / '11 Outback / '06 Tundra Location: Durham NC Posts: 510 Thanks: 6 Thanked 155 Times in 104 Posts Mentioned: 4 Post(s)	top speed in 2nd with the 225/45-15?

06-27-2013, 08:18 AM	#5
mla163 Overthinking it Join Date: May 2012 Drives: BRZ in CS Location: DC Posts: 271 Thanks: 27 Thanked 81 Times in 48 Posts Mentioned: 1 Post(s)	255/40/17 is too big. You'll lose acceleration 225/45/15 is too small. Like 10% less circumference. You may top out 2nd gear at 50 mph or so. It may work on a slow course. Even if it does, you may have brake fitment issues.

06-28-2013, 05:51 PM	#6
Turbo Den Member Join Date: Aug 2012 Drives: FRS, IS300, 911sc Location: Vancouver, BC Posts: 50 Thanks: 14 Thanked 12 Times in 7 Posts Mentioned: 0 Post(s)	with 255/40/17 ... accelerate earlier without spinning the rear. at 225/45/15... accelerate faster, but probably later to avoid spinning the rear. i have a 22mm whiteline front sway bar, softest setting.

06-28-2013, 06:25 PM	#8
GTM_Challenge Join Date: Aug 2012 Drives: On track Location: Chicago Posts: 527 Thanks: 120 Thanked 285 Times in 166 Posts Mentioned: 5 Post(s)	Did the OP mean 225/45/17?

06-30-2013, 04:53 PM	#9
Turbo Den Member Join Date: Aug 2012 Drives: FRS, IS300, 911sc Location: Vancouver, BC Posts: 50 Thanks: 14 Thanked 12 Times in 7 Posts Mentioned: 0 Post(s)	Nope. 225/45/15 is correct. 15". We know 15" wheels will fit. Just a matter of tire size dilemma.

User Name		Remember Me?
Password