Hoosier R7 - ACR Questions

[CarbonDan]

For those running Hoosier R7s on their ACR-E:

My goal is to maximize the number of heatcycles exclusively for HPDE/trackday day use. I will gladly sacrifice tracktimes (within reason) to get more heat cycles out of a set of tires (I'm out to have fun, not set track records).

- What sizes front and rear do you recommend (18" wheels vs 19" stock wheels)?
- Do the 295/30/19 and 345/30/19 R7s on stock ACR wheels create any ABS/TC issues?
- How many heat cycles are you getting out of a set of R7s?
- Any variations beyond the recommended factory 'track suspension/aero settings'? Should I make any starting adjustments going from V720s to R7s to get me in the right ballpark before I start fine tuning?

Any input is appreciated!
47111

[LuvSpeed]

If you are trying to get the most heat cycles out of a decent performance tire, I would consider Toyo Proxy RR. Not as fast as R7s (maybe a second or 2 slower), but I had 22 heat cycles out of my first set before I corded my left front tire. I currently am at 23-24 heat cycles on my second set and have not corded a tire yet. I have done a better job with rotating them. I set my personal best at High Plains Raceway on the tire with about 17 heat cycles. Also, the tires cost about $600 less than R7s for a set. I am currently tracking a TA 2.0, not an ACR. I only had around 15 heat cycles out of R7s when I previously used that tire.

Here are my calculations of the various tire ratios for commonly used tire sizes. The stock tire ratio (front diameter/rear diameter) is 0.912. It appears that you might have TC/ABS issues if you go above a 0.944 tire ratio as Viper George has mentioned on these forums he had problems on his 2015 TA 2.0 with running 315 Hoosier R7 up front. Another advantage of running Toyo Proxy RR besides being less expensive and more heat cycles is that you can run 315 up front without having TC/ABS problems. That is my current setup.

Tire Ratio

PZeroCorsa 295/355 Tire Ratio: 0.912 (stock OEM)
r888R 295 front/345 Tire Ratio: 0.919
r888R 315 front/345 Tire Ratio: 0.938
Hoosier R7 295 front/345 Tire Ratio: 0.944 (I have used this combination with no TC/ABS issues)
Hoosier R7 315 front/345 Tire Ratio: 0.955. (Viper George has reported TC/ABS issues with this combination on a TA 2.0)
Proxes RR 295 front/345 Tire Ratio: 0.919
Proxes RR 315 front/345 Tire Ratio: 0.938
Proxes RR 18" 295/345 Tire Ratio 0.909 (Forgline 18" front and rear rim calculation)
Proxes RR 18" 315/345 Tire Ratio 0.927 (Forgline 18" front and rear rim calculation)

Edit: I just realized that you have 19" rims up front. I forgot the ACR has this so the Ratio information may not help you as much. Sorry. You could still do a calculation to make sure you are staying around 0.944 or lower.

[sharmut]

I run 315x30x18 R7s on the ACR-E majority of the time and get 20 heat cycles out of a set. They feel great the first session and slowly drop off from there. The next noticeable drop off point for me is at ~10th-15th heat cycle, then again after the 15th-20th.
Last year I tried 295x30x19 and 315x30x19 R7s wanting more brake caliper to inner wheel barrel clearance and noticed the traction-control (track-mode) occassionaly activated in certain corners, where the 315x30x18 never did. I ran the following session with TC completely off and no issues.

My ride height is set to track height based on the 295x30x19 R7s and do swap between 315x30x18 depending on tire conditions.

[CarbonDan]

If you are trying to get the most heat cycles out of a decent performance tire, I would consider Toyo Proxy RR. Not as fast as R7s (maybe a second or 2 slower), but I had 22 heat cycles out of my first set before I corded my left front tire. I currently am at 23-24 heat cycles on my second set and have not corded a tire yet. I have done a better job with rotating them. I set my personal best at High Plains Raceway on the tire with about 17 heat cycles. Also, the tires cost about $600 less than R7s for a set. I am currently tracking a TA 2.0, not an ACR. I only had around 15 heat cycles out of R7s when I previously used that tire.

Here are my calculations of the various tire ratios for commonly used tire sizes. The stock tire ratio (front diameter/rear diameter) is 0.912. It appears that you might have TC/ABS issues if you go above a 0.944 tire ratio as Viper George has mentioned on these forums he had problems on his 2015 TA 2.0 with running 315 Hoosier R7 up front. Another advantage of running Toyo Proxy RR besides being less expensive and more heat cycles is that you can run 315 up front without having TC/ABS problems. That is my current setup.

Tire Ratio

PZeroCorsa 295/355 Tire Ratio: 0.912 (stock OEM)
r888R 295 front/345 Tire Ratio: 0.919
r888R 315 front/345 Tire Ratio: 0.938
Hoosier R7 295 front/345 Tire Ratio: 0.944 (I have used this combination with no TC/ABS issues)
Hoosier R7 315 front/345 Tire Ratio: 0.955. (Viper George has reported TC/ABS issues with this combination on a TA 2.0)
Proxes RR 295 front/345 Tire Ratio: 0.919
Proxes RR 315 front/345 Tire Ratio: 0.938
Proxes RR 18" 295/345 Tire Ratio 0.909 (Forgline 18" front and rear rim calculation)
Proxes RR 18" 315/345 Tire Ratio 0.927 (Forgline 18" front and rear rim calculation)

Edit: I just realized that you have 19" rims up front. I forgot the ACR has this so the Ratio information may not help you as much. Sorry. You could still do a calculation to make sure you are staying around 0.944 or lower.

Wow super helpful info, thanks! Before I got my trailer, I was digging heavily to get more info on the R888r as they are technically streetable. The price is definitely right on them too. I'm going to look into that more.


I run 315x30x18 R7s on the ACR-E majority of the time and get 20 heat cycles out of a set. They feel great the first session and slowly drop off from there. The next noticeable drop off point for me is at ~10th-15th heat cycle, then again after the 15th-20th.
Last year I tried 295x30x19 and 315x30x19 R7s wanting more brake caliper to inner wheel barrel clearance and noticed the traction-control (track-mode) occassionaly activated in certain corners, where the 315x30x18 never did. I ran the following session with TC completely off and no issues.

My ride height is set to track height based on the 295x30x19 R7s and do swap between 315x30x18 depending on tire conditions.

This is perfect, exactly what I was hoping to hear!
It's super interesting to me too that you're swapping between the 19 and 18" wheels... I'm in a transition period where I have 1 set of 19" wheels with the oem Kumhos on them, multiple sets of additional OEM V720s that I need to burn through. If the characteristics of the car are reasonably consistent between a 19 and 18" set of wheels without any additonal setup changes, that gives me a great opportunity to buy a set of 18" wheels with 315/345 R7s and get acquainted with them.

-What specific 18" wheel model and specs do you run?
- ABS, TC, and inner wheel well wear are all perfectly fine when running 315/345 R7s, 18" wheels, and OEM track suspension settings?
If yes to the above, that seems kind of like as good of an option and I'll ever find..

[sharmut]

The 18" wheels are BC-Forged RZ39(18x11 offset +40 & 19x13 offset +71).
The 19" wheels are Forgeline GTD-1 Viper (19x11 & 19x13) don't know the offset, but suspect the front is a bit more aggressive than OE.
Both combination rubs against the front passenger inner fender liner. The 19'' setup rubs against the outer passenger fender/fascia on high speed left-hand turns, which I addressed by increasing the front passenger shock compression 1 click.

[LuvSpeed]

Wow super helpful info, thanks! Before I got my trailer, I was digging heavily to get more info on the R888r as they are technically streetable. The price is definitely right on them too. I'm going to look into that more.

The tire I was recommending was the Toyo Proxy RR not the r888r. The RRs are not streetable. The RR’s are cheaper than the R7s, however the r888r are about the same price as the R7s. The RRs are about 1-2 seconds faster than r888r in my opinion.

[TheWessss]

I have been running R7's for years with great success on my ACR-E. All good info here, but if you really wanna talk to the man. Contact Jim at www.trackdaytire.com one of our newest VOA sponsors and I know he has a discount code for our VOA members. Guy knows so much about tires and can match you with the right set of slicks. BTW, I consistently get 7 or more track days out of a set, I think that is great value. I'm fast but I too don't look for every last second at the expense of my brakes and tires.

[Lawineer]

Tires are just going to get harder and harder as they heat cycles. You can use them the same- heck they'll last longer. That goes with pretty much any tire.
I don't get why people like R888R so much. They're loud AF and the grip isn't that good plus their grip is extremely sensitive to pressure. They were substantially (2-3 sec) slower than cup2 for me. They're basically a Super Sport that won't overheat as fast.

I also don't know you guys get even 4 track days on a set of slicks on a car like this. I would be lucky to get 3-4 track days on "track day tires" (R888R, NT01, etc) in my C7. We'll see how my Pzeros hold up after a track day. Would love to have less than 20% of the tread gone!

[Pappy]

I have run both R-7s and A-7s - 18" Finspeed wheels with 335/30s (12" wheel) on front, 345s (13" wheel) rear. Early on I had a couple of traction control issues, but it almost acts like the car "learned" the differences in tire diameters and I haven't had a problem since. No real rubbing, except at full lock, but I do have some significant scoring of the front wheel barrels from rocks between the caliper and barrel. The A-7s don't seem to wear a lot faster than the R-7s, but they do provide a lot more traction. This is all fairly tight road course stuff - no autocross. AZ VPR would be the expert for this discussion - he has been through a lot of tire combos.

Pappy