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RR Tire Wear $$$
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TOPIC: RR Tire Wear $$$

Re: RR Tire Wear $$$ 11 years, 6 months ago #15654

  • ChuckS
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Forgot to add - Third set is a week 50 build.

My limited tire temps, indicate that I do need a little more camber.

Charlie's tire wear and camber settings also seem to indicate that his set up likes about what mine will want - or maybe a little less for me.

One of the guys from Las Vegas was running around -2.1 at Cal Speedway - PCA Festival of Speed this weekend and not having wear issues, but he did say that he noticed a degradation of traction beginning around 6 heat cycles. He was also running lower tire pressures. Did not make sense to me, but everybody has different chassis set ups, so we may see different data that works for some people.

Initial testing had me targeting 38-39 psi hot, but now (with different tracks) it is looking like 37 hot is better.

What are others finding for tire pressure?
Chuck Sharp
San Diego, CA
1986 Spec 944 #58
Red / Twin White Stripes
Last Edit: 11 years, 6 months ago by ChuckS.

Re: RR Tire Wear $$$ 11 years, 6 months ago #15655

  • Bottoz
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Here's what we're seeing in the RM Region:

We have week 32 and week 50 tires. Week 50s are fine. Week 32s have separation after 2 races. Passenger rears start first, then drivers rear. After proper rotation, new separation starts on the freshly rotated rears.

As said earlier... love the grip, hate the wear issues.
C.J. Botts
1984 944 #37

2007 RM HPDE Driver of the Year
2010 RM Instructor of the Year
2013 RM 944SPEC Director

Re: RR Tire Wear $$$ 11 years, 6 months ago #15656

  • cbuzzetti
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I shoot for 37-38 hot. Seems to provide the best performance. I have noticed that tire pressure does not seem to make that much difference in the tire temps. This must be due to the stiffer side wall and I am guessing possibly a stiffer running surface.

I will see if I can scan my data sheets and post them here.
2018 NASA 944Spec National Champ
2018 NASA ST5 P2 944 Nationals COTA
2017 NASA 944Spec WSC P3
2016 NASA PTD-944 WSC P2
2015 NASA GTS1 Western Champion
2014 NASA 944Spec Western Champion
2013 NASA 944Spec So-Cal Regional Champion
2013 NASA 944Spec National P3
2010 NASA GTS-1 National Champion
2010 NASA 944Spec National P3
2010 NASA So-Cal 944Spec Regional Champion
2009 NASA 944Spec National Champion

Re: RR Tire Wear $$$ 11 years, 6 months ago #15660

  • cbuzzetti
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OK so I checked my date codes and all my tires are 3212. All bought at the same time in December.

My quickest lap of the weekend was in qualifying Saturday at a 2:05.056

The old lap record was a 2:08.486 on RA1s over 10 years ago.

The tires had 6 sessions on them and have never been rotated. they now have 11 sessions including 1 hr and 20 minutes of an enduro at sprint racing speeds and the RF tire looks like it is just starting to cord. All other tires look good. I have never rotated these tires and that would have extended the life of the RF for sure. The config we were running is hard on the RF.

temps and pressures for that session are

LF press. 36.5 RF press. 36
temps 129 132 147 Temps 144 134 128

LR press. 35 RR press. 35.5
temps 139 147 156 temps 149 150 145

So you can see that I did not get to my desired pressure. I ran one other session over the weekend that had higher temps, most sessions had lower temps. In most sessions the pressures were in the 35-36 range. Ambient temp was around 75 degrees for Q and Race.

Does anyone know what the optimum tire temps and pressures are from TOYO?

I will say that because these tires do not have a tread across the surface it is more difficult to see the wear developing. This may be the leading cause of cording the edge.
2018 NASA 944Spec National Champ
2018 NASA ST5 P2 944 Nationals COTA
2017 NASA 944Spec WSC P3
2016 NASA PTD-944 WSC P2
2015 NASA GTS1 Western Champion
2014 NASA 944Spec Western Champion
2013 NASA 944Spec So-Cal Regional Champion
2013 NASA 944Spec National P3
2010 NASA GTS-1 National Champion
2010 NASA 944Spec National P3
2010 NASA So-Cal 944Spec Regional Champion
2009 NASA 944Spec National Champion

Re: RR Tire Wear $$$ 11 years, 6 months ago #15661

I'll be out for the first time on them this weekend at Thunderhill. I have them mounted correctly, haven't looked at the dates yet for when they were made.

With RA-1s, I usually ran -3.0 to -3.25 camber front and -2.5 rear with 1/8" toe out front and zero rear. Toe can be a big factor in tire wear as well.

For the RR's, I've gone to more front camber, starting at -3.5 but I doubt I'll have a lot of time to test. All other settings the same. I wouldn't be surprised if they like a lot of camber, similar to a Hoosier.

Charlie, how much camber were you running with RA-1s and how much toe?

Despite claims to the contrary, I can't imagine that a higher grip tire will equal the life and "forgiveness" of a lower grip tire.

Re: RR Tire Wear $$$ 11 years, 6 months ago #15662

Thanks for putting the info out there - interesting!

Here are Toyos recommendations for the tire:

Operating Temperature: 160°F to 220°F
Hot Inflation Pressures: High 30s to Low 40s (psi)
Camber: -2.5° to -5.0°
Caster: As much positive as possible


These recommendations are for a fairly broad range, and are identical to the RA-1, FWIW. There may be aspects to our specific application that are different
We run a wider tire the same width rim as SM, and SE30, for example.

Digging around Toy's website, I came up with a SM setup guide (see below). It is meant for the R-888, but has some useful generalizations for doing tire temp testing. The presssures and camber settings that they recommended there are very different than the RA-1, or RR.

Spec Miata Setup Guidelines
...................................

Air Pressure
The R888 can be used at lower hot pressures as compared to the RA1 because of its design.
Decreasing the air pressure will improve contact pressure and footprint shape. A recommended hot
pressure range is 32 – 38 psi. For a light weight vehicle such as the Spec Miata, 32 psi hot is a good
starting point.
Tread Temperatures
The optimum tread temperature for the R888 is 160°F to 220°F. Below 140°F and above 250°F the tire
may not provide sufficient grip. Generally there will be a 25°F temperature gradient from inside to outside
shoulder, with the inside shoulder being the hottest. Most distance and time on a race track is in a
straight line therefore, the inside shoulder is hottest because of negative camber. The same
temperatures across the tread face should not be expected.
Understand the track layout before pit entry. If for example there is a long right hand turn before entry, the
left tires will be hotter. Take tire temperatures and pressures after a few laps to get the temperatures and
pressures stabilized and come in after a hot lap.
Camber
To maximize the potential of the RA1 a lot of negative camber might have been required. The R888 on
the other hand produces more camber thrust at the same camber angles as the RA1, therefore less
negative camber might be beneficial. Reducing negative camber will improve contact pressure
distribution across the tread face improving wear. Start at -2.5° in the front and -3.0° in the rear.
Analyzing the tire temperatures, wear, and chassis behavior will help you dial-in the optimum camber for
your setup.
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd
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