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Old 08-12-2016, 02:15 PM   #1
fzss
 
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Bridgestone Potenza RE-71R 305/30R-19 (new size) Discussion Thread

Figured this would be more appropriate in its own thread.

I just burned through a set of 285/35R-19 RE-71Rs on my 19x10 front 19x11 rear MRR FS01 wheels. They lasted about 60 autocross runs. INCREDIBLE tire, instantly shaved 1.5 to 2 seconds off my regular times. Car runs CAM-C class.

I'm definitely going to purchase another set. With the new sizes being released, I'm torn whether to run a square 305/30R-19 or a staggered 285/35R-19 front 305/30R-19 rear.

I'd love to run a square 305/30R-19 however I'm worried about clearance on turn-in. These Bridgestones run very wide.

I'm admittedly very under-prepared for CAM-C. Up front I'm running stock shocks with BMR 1.25" lowering springs and BMR sway bar. I have about -1.5 degrees camber dialed in up front, no toe.

Can anyone with a similar setup chime in? I've heard a staggered setup isn't always ideal for autocross.
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Old 08-12-2016, 05:11 PM   #2
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Quote:
Originally Posted by fzss View Post
Figured this would be more appropriate in its own thread.

I just burned through a set of 285/35R-19 RE-71Rs on my 19x10 front 19x11 rear MRR FS01 wheels. They lasted about 60 autocross runs. INCREDIBLE tire, instantly shaved 1.5 to 2 seconds off my regular times. Car runs CAM-C class.

I'm definitely going to purchase another set. With the new sizes being released, I'm torn whether to run a square 305/30R-19 or a staggered 285/35R-19 front 305/30R-19 rear.

I'd love to run a square 305/30R-19 however I'm worried about clearance on turn-in. These Bridgestones run very wide.

I'm admittedly very under-prepared for CAM-C. Up front I'm running stock shocks with BMR 1.25" lowering springs and BMR sway bar. I have about -1.5 degrees camber dialed in up front, no toe.

Can anyone with a similar setup chime in? I've heard a staggered setup isn't always ideal for autocross.
I know 'bruhop' on this forum runs 305/35/20 RS3v2 Hankooks all around on his 1LE. PM him, not 19 inch wheels but may help with clearance issues.
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Old 08-12-2016, 05:54 PM   #3
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Originally Posted by JRL1LE View Post
I know 'bruhop' on this forum runs 305/35/20 RS3v2 Hankooks all around on his 1LE. PM him, not 19 inch wheels but may help with clearance issues.
Thanks, PM sent.
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Old 08-12-2016, 08:47 PM   #4
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I have track wheels which are 19"x10.5" ET22 with OEM Z28 Trofeo R's on them, 305/30R19. They fit fine, although I haven't tracked them yet
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Old 08-12-2016, 09:05 PM   #5
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I'm running z28 wheels with 305/30-19 on my lowered 1LE with no issues...
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Old 08-13-2016, 01:56 AM   #6
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Oh, I posted this reply on that other thread. Here it is again:

I don't recommend messing with your balanced setup by introducing staggered tires. More grip in the rear = understeer. Then you'll have to spend a bunch of time and testing to tune out the understeer via tire pressures, sway bars, springs, shocks, offsets etc.

305/30/19 square will be fine. Try playing with a wheel and tire calculator if you are worried.

Here is a known aggressive setup that works:
18x12 ET30 front and back + 30mm spacer in the front
335/30/18 Rival S tires

Based on this pioneer (Cornercarver). He got to his specs by comparing backspacing with the Z/28 wheels. Backspacing specs that JPSS perfected before the Z/28 came out:
http://www.camaro5.com/forums/showpo...7&postcount=20
http://www.camaro5.com/forums/showpo...&postcount=125

I'm going to run 305/30/19 on 19x10 ET16 in the front. This is how it compares: https://www.rimsntires.com/specspro....inite:%20Front

I'm going to run 305/30/19 on 19x11 ET36 in the rear. This is how it compares:
https://www.rimsntires.com/specspro....finite:%20Rear
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Old 08-13-2016, 04:00 AM   #7
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I'm not a big fan of running spacers on a track car, especially a 30mm one which is pretty thick.
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Old 08-13-2016, 04:45 AM   #8
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Originally Posted by clarkkent View Post
I'm not a big fan of running spacers on a track car, especially a 30mm one which is pretty thick.
The spacer is unique to Cornercarver's setup. 4 same-sized wheels means he can rotate. For autocross, a 30mm spacer is fine. Even better if it's an adapter that bolts to the hub vs spacer.

Sounds like fzss already has wheels. Whatever offset he chose for them, should be able to fit 305/30/19 tires safely.
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Old 08-13-2016, 10:02 AM   #9
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Quote:
Originally Posted by nilfinite View Post
Oh, I posted this reply on that other thread. Here it is again:

I don't recommend messing with your balanced setup by introducing staggered tires. More grip in the rear = understeer. Then you'll have to spend a bunch of time and testing to tune out the understeer via tire pressures, sway bars, springs, shocks, offsets etc.

305/30/19 square will be fine. Try playing with a wheel and tire calculator if you are worried.

Here is a known aggressive setup that works:
18x12 ET30 front and back + 30mm spacer in the front
335/30/18 Rival S tires

Based on this pioneer (Cornercarver). He got to his specs by comparing backspacing with the Z/28 wheels. Backspacing specs that JPSS perfected before the Z/28 came out:
http://www.camaro5.com/forums/showpo...7&postcount=20
http://www.camaro5.com/forums/showpo...&postcount=125

I'm going to run 305/30/19 on 19x10 ET16 in the front. This is how it compares: https://www.rimsntires.com/specspro....inite:%20Front

I'm going to run 305/30/19 on 19x11 ET36 in the rear. This is how it compares:
https://www.rimsntires.com/specspro....finite:%20Rear
FYI most 305/30-19 tires are recommended 10.5-11.5 wheel. putting them on a 10" is going to cup them a little and be the equivalent of running a narrower tire... best to have 11" in front and 11.5 in the rear
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Old 08-13-2016, 11:48 AM   #10
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Originally Posted by brokencilence View Post
FYI most 305/30-19 tires are recommended 10.5-11.5 wheel. putting them on a 10" is going to cup them a little and be the equivalent of running a narrower tire... best to have 11" in front and 11.5 in the rear
SCCA rules force people to do not-optimal things! Can't change wheel width per the rules. Only 1" decrease in wheel diameter and push the wheels 7mm out with offset.

Luckily the RE-71R has a super stiff sidewall. It'll handle being pinched on a wheel much better than most.

A decent comp is what the guys in 2016 Camaros are doing. They are running 275/35/19 RE-71R on 19x8.5 front and 19x9.5 rear.
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Old 08-14-2016, 06:44 PM   #11
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Talking about CAM not STREET
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Old 08-15-2016, 07:59 PM   #12
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Thanks everyone for your personal insight.

I think I'm going to be the guinea pig and run a 305/30R-19 square. CAM class has no restrictions for wheels, however I already have a set so I'm just trying to work with what I have. The fronts (19x10) have a 23mm offset and the rears (19x11) have a 43mm offset. Going to probably order a couple 5mm spacers for the fronts just in case.
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Old 08-15-2016, 08:07 PM   #13
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Guinea Pig??? We have been running 305/30/19 RE-11s since 2009. We are running 325/30/19 RE-11s as well. I seriously doubt the 305/30/19 RE-71 will rub ;-)

325s





305s on these two...

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Old 08-15-2016, 08:10 PM   #14
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Guinea Pig??? We have been running 305/30/19 RE-11s since 2009. We are running 325/30/19 RE-11s as well. I seriously doubt the 305/30/19 RE-71 will rub ;-)

325s





305s on these two...

Whelp, that makes me feel much better about this! Thanks!
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