BFG Rival S 1.5 unusual wear?
 

Hello MT.net. I'm posting to document my tire failure so hopefully others can learn from my mistakes and help me avoid future ones.
I've run these 225 Rivals on a 15.8 tire with an aggressive alignment of 3.2 front, 2.7 rear. Only Rear total toe: + 1/8". Suspension is Xida Race with 800/500 springs. This is a slightly more aggressive Dual Duty Super Miata alignment. On the 5th track day, the outside front tire saw severe delamination. I was running 34-36 PSI hot throughout the day.
I believe the failure was due to inadequate tire pressure causing extreme tire rollover and outside shoulder wear. The intact rear outside tire (right side on thunderhill) has extra outside wear along the outside, and shows wear marks along the vertical edge of the tire. At some point, the front tire couldn't cope with the wear and the tire roll-over, and completely delaminated. I noticed immediately due to the vibration and sudden understeer. Once i pulled in, I saw this carnage :eek4:. I'm fortunate I didn't go off and was able to drive home.
Corrective actions I'm thinking of taking:

• I realize now I should have spent that $100 on a tire pyrometer to avoid scrapping these $600 tires. Pyrometer already on order. I'll check temperatures and adjust accordingly.
• Accurate tire pressure gauge - none of the gauges in my garage agree with each other. I've ordered a digital one that I'll use exclusively for track use to keep consistent.
• Tire chalk - should i be chalking the tires to spot roll-over before the wear gets bad?
• Larger wheels - I plan on moving to 9" wheels to get a BBK eventually. Will this help the next set of tires?
• Pulling the fender liner - I completely forgot to remove or trim these. They have significant wear due to the extended travel of the xidas. I'll do this before the next track day
• Running higher pressure (especially on the outside front) - it seems i'm driving the car more aggressively with the new suspension, to the point I need to be very aware of tire issues like this, and take appropriate corrective action.
• Re-filling tires to their correct pressure before driving home - I'm very guilty of this.

Any other suggestions? Agree or disagree with my assessment? I've already got a set of 225 RS4s waiting to go on :likecat:.

https://cimg0.ibsrv.net/gimg/www.mia...90b09a14fa.pngShoulder wear
https://cimg1.ibsrv.net/gimg/www.mia...0a60980a75.pngAbrupt Delamination
https://cimg3.ibsrv.net/gimg/www.mia...c910cf9003.pngTire roll over

How much sway bar do you have?

You corded the tire because you didn't have the car or the tire setup right. Certainly not a defect.

It sounds like you learned your lesson.

225 is also too wide for an 8" rim according to the powers that be.

Do you have stock bushings still?? Impossible to dial in enough static negative camber to make up for worn out soft bushing deflection on track.
Recheck your alignment, many shops fudge and don't second check toe.
A good track alignment will kill tires inside edge on the street, and a good street alignment will kill the outside of tires on track.
RS4's do wear great.


8" and 225 is plenty for any street tire, many shops wont mount a 225 on a 9" wheel for street use.

"Remember to ensure maximum performance vehicle set-up, tire pressure, and temperature monitoring is imperative. Rival S is primarily intended as a low-speed autocross tire. Use on road courses in time attack formats requires proper care and feeding."

Get that pyro into duty asap. Set your pressure based on temp reading for maximum performance. Maximum tire life or treadwear will require a different pressure strategy. BFG says to run them high for even treadwear, but you'll be running them low on 9" wheels for maximum pace.
Rotate your tires between events/days/sessions to promote more even tread wear. Dont leave the RF tire on the RF every session for two days and expect it to wear the same as the left rear.
If they're overheating, like the delaminated one did, dont run all 20-30 minutes without knowing how to keep them cool. A tire like the RivalS will be way off its happy plateau by lap 5 without conscience cool-down laps/efforts.

When they get greasy you have exceeded the design parameters and need a full cool down lap. Otherwise you're just smearing the rubber off onto the surface.

Thanks for the good feedback, all. Somehow I missed the responses to my own thread. I moved to the Supermiata Big Grip kit when i moved to these tires. In hindsight, the extra grip is what allowed me to cook my tires.
I'm trying every solution: I bumped my front camber from 2.6 to 3.2 and the rear accordingly. I'm pretty sure the bolts slipped as it was supposed to be at 3, so new bolts will go in shortly. I've messaged SadFab for some baller Delrin bushings as the oem rubber bushings are completely shot. Pyrometer measurements are now good, roughly even at 32 psi hot on 8" with RS4s.

G-Force Rival comes in 3-4 versions.
R1 is Rcomp
Rival is for street and road coarse
Rival S is for street and Autocross with emphasis on autocross
Rival S 1.5 is a TireRack exclusive that has additional wet traction. (so I was told by BFGoodrich, but I think I have seen it other places)

Doesn't look like you had a lot of rollover. What kind of track were you on? For instance, Pueblo Motorsports Park near me is notoriously hard on your left front tire. Could be something similar for you. Were the tires feeling greasy out on track?

Looks like it just got overheated. That blueish color...

R1 is not part of the rival line. Yes the original Rival is ment for track duty or heavier cars and not really used much on miata's, it's actually hard to find these in stock. The Rival S and Rival S 1.5 are very very similar with the 1.5 having a revised carcass design as well as slightly softer rubber, this version was introduced after getting their ass handed to them at nationals by the RE-71. With the introduction of the 1.5 I'm not even sure they still make the regular S.

I've seen it reported the Rival S will last 5-10 hrs on track depending on driving style. The RS4 has been reported to last a full 24 hr enduro and my experience with them backs that up. I've got 15hrs, 20 auto-x events, 3,000 street miles and still would have life left if I hadn't ran them on too narrow of wheels for a while. They are also 2 seconds a lap slower than the rival S.

You don't want even temps across the tire. You want 10*F difference between inner and mid, and an additional 10* between mid and outer. (example of good temp spread for rival s, which have a 170-190 temp sweet spot, iirc, is 185*F inner, 175*F middle, and 165*F outer)

If you didn't know already, the alignment bolts need to be very tight on a high grip setup. Like use a 1.5 foot bar tight. You only get 2 or so alignments at this level, as the bolts eventually just yield.

Thump. to be truly helpful, it would be good to specify if temps are to rise going from inside to outside, or fall from inside to outside; or peak in the middle... your statement is true, but incomplete.

Oh yeah, you right. Fixed :)