ptindall

My brother recently bought a set of BFGoodrich g-force R1's for his MR2 track car. Yesterday was the first time either him or me had ever ridden in a car with true track tires. He drove, I rode. We were both astonished not only at the grip but also how much more settled and stable the car felt. Here are a couple pics.





The problem came in the second session. Even from the passenger seat, I noticed a drop off in grip. My brother agreed. He ran two more sessions for a total of four. The last session I sat out so he was ~150 lbs lighter in a 2100 lbs / 112hp car. Plus over the sessions, he clearly improved his driving line and broke later and later, yet after the second session, his lap times dropped off about 1 second for the third session and another 1 second for the last session. We have no expirience with race tires at all. Is it normal for tires to lose grip significantly after their very first session and continue to tail off? Or does this have anything to do with it?







When he ran this car on street tires, it collected these beads of rubber so bad that the car shook badly. Now with these tires, it does eject rubber going down the straight but is still collecting a thick longitudinal bead of rubber. Any help as to how normal this is, how it affects performance, what can be done about it, etc would be greatly appriciated. Thanks guys.

Oh yeah, the front tires collect rubber in the center while the rears collect it towards the inside edge.

AU N EGL

Collecting and melting rubber eh?

Too much air in the front tires and too little in the rear tires would be my first impression.


Just take a hair drier or heat gun and metal paint scrapper, heat up that rubber deposit and scrap it off.

ptindall

They had 34psi cold in all four. Are you suggesting scrapping the rubber off between sessions at the track, or that we could eliminate the problem just by changing tire pressure? Thanks for your help.

John Shiels

get them hot on track and the rubber will go off. Then try to stay in cleaner areas not off the line where marbles collect.

ptindall

ttt for possibly more insight into the cause of loss of grip and why these tires are collecting rubber so badly.

robvuk

This is interesting. I've never seen that before. I was going to say that maybe he's not driving hard enough but it looks like the tires are scrubbed up good. No other thoughts at this time.

On the upside. Think about how long those tires will last.

97C5inSD

Well i don't have any personal experince with these tires but one of our really good drivers in our local car club used them for autocross and he seemed rather happy with them at the beggining of the year. but as the year went on he felt the grip was falling off of them faster then it should considering the tread that was left. especially after he put on a new set of hoosiers. May just be that BFG's are good at the begining but just fall off a bit faster and more then the other common tires?

Kanmer

Were you checking pressures after your run and before the next? The lack of grip suggests too much air. Race tires are very sticky and will collect almost anything they run over. Those will clean up when they get to temp and get a little scuffing. Mine look like that , not quite that bad, when I get home.

Bob

0Vector Vette

Race tires pick up everything. When you get them hot on the track, all that rubber will come off. You pick up more mostly on cool down laps when not on the racing line. I have tried the BF Goodrich tires in the past and found the same rapid drop in performance. My suggestion, buy the best racing tires on the market, Hoosier!!!!

ptindall

First off, thank you soo much everybody for the responses. No, we were not checking pressures between sessions. I just checked them once before the day started to get a base line. Our idea was to just get some seat time and get comfortable with everything. Once settled in and used to the car, then start making changes to things like tire pressure and see what happens. I thought 34psi was high myself but my brother got 35psi some from source. What do you guys run?

ptindall

I have tried the BF Goodrich tires in the past and found the same rapid drop in performance. My suggestion, buy the best racing tires on the market, Hoosier!!!![/QUOTE]

Some rubber was coming off on track, but not more than it was picking up. Is it possible the car just isn't getting the tires hot enouph because it probably wieghs 2100 lbs or less and has less than 112hp? After a 5/8 mile striaghtaway, it was only hitting 95mph and only having to slow to 65 for turn 1. (My Z06 is about 135mph to 55mph for the same corner) Nearly no braking was required. Hmmmm.... maybe it's time for an engine swap so he can just get the tires up to tempature.



Wow, that sucks. That's a whole lot of money for one good session.

ptindall

We're pretty certain these tires look just like this while he's running because the car and the steering wheel shook from the unbalanced/ out of roundness from about midway through the second session on. Plus we only get about 1/2 lap of cool down.