RE71R vrs Hoosier Tires
10-09-2016, 01:01 PM
#1
Three Wheelin'
Thread Starter
RE71R vrs Hoosier Tires
Before I took my GT4 to the track I installed the RE71 245/40R19 F and 285/35R19 R on OZ 8-1/2" F and 10" R wheels. I ran this setup for 3 events and recently switched to Hoosier 235/35 x 19 F and 295/30 x 19. Neither of these laps is my fastest but in both laps I had to lift and go wide at the apex of turn 11 to avoid a car entering the pits.
The green trace is the Hoosiers, and the red trace is the RE71. The first surprise was that the maximum Lateral Gs averaged about the same. Perhaps I could have got a little more out of the Hoosiers. There was a significant difference in Longitudinal Gs under braking with the Hoosiers doing 1.24 vrs RE71 @ 1.04. If you look at the speed trace you can see I broke later in most turns with the Hoosiers. The biggest difference to me was that, looking at the throttle trace, I got to full throttle earlier at the exit of most corners and this extra speed carried to the next corner. There is an exception at the top of the esses, the smaller diameter of the Hoosier rear tire let me shift sooner.
The green trace is the Hoosiers, and the red trace is the RE71. The first surprise was that the maximum Lateral Gs averaged about the same. Perhaps I could have got a little more out of the Hoosiers. There was a significant difference in Longitudinal Gs under braking with the Hoosiers doing 1.24 vrs RE71 @ 1.04. If you look at the speed trace you can see I broke later in most turns with the Hoosiers. The biggest difference to me was that, looking at the throttle trace, I got to full throttle earlier at the exit of most corners and this extra speed carried to the next corner. There is an exception at the top of the esses, the smaller diameter of the Hoosier rear tire let me shift sooner.
10-09-2016, 01:05 PM
#2
Nordschleife Master
You can't look at peak/max Gs. Transient spikes don't tell the story because of bumps, dips, and camber changes. The important number is sustained lateral G before breakaway. I find it hard to read that number with the graph output because we are only talking about a few tenths of a G and you don't know what the tires are doing. The best way to look is to overlay on video and watch the readout as you listen to the tires breaking away on a long sweeper. That will tell you the true difference.
Although, the longitudinal braking force is much easier to read on graphs, which explains why the difference between the tires is more discernable. Re71r are not Hoosier level grip. I would have guessed that Hoosiers give you 0.2 extra G of grip. My rule of thumb:
R comp like re71r, cup2, nt01 give you about 0.2 more Gs than street tires
Hoosiers give you about 0.2 more Gs than R comps
Although, the longitudinal braking force is much easier to read on graphs, which explains why the difference between the tires is more discernable. Re71r are not Hoosier level grip. I would have guessed that Hoosiers give you 0.2 extra G of grip. My rule of thumb:
R comp like re71r, cup2, nt01 give you about 0.2 more Gs than street tires
Hoosiers give you about 0.2 more Gs than R comps
10-09-2016, 02:40 PM
#3
Three Wheelin'
Bill, how did the lap times compare between the two?
more consistent times with either tire? how many laps before drop off of grip in each session?
these are the two tire choices I am planning on trialling this spring for my GT4.
On my GT3 I run 2:05's on R7's and 2:09's on Cup 2's....so 4 seconds delta.
I saw that you did a 2:09.xx on the Hoosiers with PCA last week.
more consistent times with either tire? how many laps before drop off of grip in each session?
these are the two tire choices I am planning on trialling this spring for my GT4.
On my GT3 I run 2:05's on R7's and 2:09's on Cup 2's....so 4 seconds delta.
I saw that you did a 2:09.xx on the Hoosiers with PCA last week.
10-09-2016, 04:41 PM
#4
I'll be running Hoosiers for the first time at Chuckwalla next weekend with data and video (thanks to Spyerx). Then in Nov I'll run RE71Rs and the same Hoosiers (with 9-10 HCs) at Buttonwillow. My experience has been that the Hoosiers are about 2-2.5 seconds faster than R comp tires on a 3-mile track.
10-09-2016, 07:11 PM
#5
GT3 player par excellence
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^ 10 HC hoosiers are not better than RE71
first 3HC is like taking 10 viagra at once.
get ready for the drug
first 3HC is like taking 10 viagra at once.
get ready for the drug
10-09-2016, 07:40 PM
#6
Three Wheelin'
Thread Starter
Bill, how did the lap times compare between the two?
more consistent times with either tire? how many laps before drop off of grip in each session?
these are the two tire choices I am planning on trialling this spring for my GT4.
On my GT3 I run 2:05's on R7's and 2:09's on Cup 2's....so 4 seconds delta.
I saw that you did a 2:09.xx on the Hoosiers with PCA last week.
more consistent times with either tire? how many laps before drop off of grip in each session?
these are the two tire choices I am planning on trialling this spring for my GT4.
On my GT3 I run 2:05's on R7's and 2:09's on Cup 2's....so 4 seconds delta.
I saw that you did a 2:09.xx on the Hoosiers with PCA last week.
10-09-2016, 08:13 PM
#7
Track Day
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Thanks for the comparison and data. I just got my re71r's in 245/295 on my GT4 yesterday and can't wait to try them out!
Were you running similar tire pressures? I'm curious to know what pressures you recommend with the re71r.
Were you running similar tire pressures? I'm curious to know what pressures you recommend with the re71r.
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10-09-2016, 11:23 PM
#8
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I think that What previous posters have said is right in that Hoosiers will give an extra 0.2 Gs and a 2 sec benefit per minute.
Don't forget the Hoosiers might also get you no warranty coverage if something happens on track.
Don't forget the Hoosiers might also get you no warranty coverage if something happens on track.
10-10-2016, 12:05 AM
#9
Awesome data for Watkins Glen. 2:13 is pretty damn good. When I read your data I see that you're over slowing with the RE71s compared to the Hoosiers. I also noticed when running the RE71 you lifted as you went through 2-3 and again leading up to 4 (using your loaded turn numbers). Turn 1 and 7 are the only corners you were able to get on the throttle faster than the Hoosiers. I'm curious if you're not feeling the grip as quickly, or are you not as confident in the tires as they exit a corner. I bet if you can stay in the throttle through the Esses you can easily hit 2:12s. Great stuff!
10-10-2016, 09:46 AM
#10
Three Wheelin'
Thread Starter
I settled on 33 F and 35 R hot on the RE71 and about a pound higher on the Hoosiers.
10-10-2016, 11:37 AM
#12
Rennlist Member
hoosiers will want 1 degree more camber give or take depending driver and track...
10-10-2016, 12:24 PM
#13
Three Wheelin'
Thread Starter
10-10-2016, 01:27 PM
#14
Three Wheelin'
Awesome data for Watkins Glen. 2:13 is pretty damn good. When I read your data I see that you're over slowing with the RE71s compared to the Hoosiers. I also noticed when running the RE71 you lifted as you went through 2-3 and again leading up to 4 (using your loaded turn numbers). Turn 1 and 7 are the only corners you were able to get on the throttle faster than the Hoosiers. I'm curious if you're not feeling the grip as quickly, or are you not as confident in the tires as they exit a corner. I bet if you can stay in the throttle through the Esses you can easily hit 2:12s. Great stuff!
10-10-2016, 04:33 PM
#15
