Lousailor

There are plenty of inexpensive performance tires out there. You don't want cheap, because cheap means cheaply made; they will not last or perform and could be a safety hazard in performance conditions. I also agree with the others in that the goal is not to come 'out of the box' as the fastest. Learn your car and it's limits with the solid inexpensive street tire, and when you're ready you will know how to exploit the increased performance of a really good performance set-up.

Matt H

Lou - there are lots of inexpensive performance tires out there, there are VERY few good inexpensive performance tires made. You guys think they cost a lot more just because we can? Why is a Michelin PS2 or BS Potenza S-03 cost more than a Kumho? (lots of reasons actually) Darn sure isnt because we just thought the higher price tag meant more sales :>)
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M758

On the subject of tires.

I did a PCA club race at PIR this weekend and in addition to racing I also instructed a fellow in a 944 Turbo. Car had chip, MAF and i'd guess 15 psi boost. Some thing like 310 flywheel hp. Nice car.

I was this gentleman's first time to Phoenix International Raceway. He had done I think 1 DE before.

He was running on a set of new heat cycled Kumho Victoracers.

Well first session out there was alot of traffic and we went slow since he had to learn the line. We in fact got passed by 924S on street tires. As day went on we started to go faster as he got the line better. I was always careful to give him extra feed back on understeer and oversteer since he was running these tires. Their stick make for little feed back as to what the car was doing. I was aware, but I am sure he was not. By the end of the day we were the fastest car in the DE group and he was a safe competent driver probably getting about 95% of the line right. That last 5% is very tough. A foot here and there is all he was missing. While he did good I still have to wonder how much of this was from the tires? Hard to say, but I do know that we were the fastest car in the session due to tires, power, and good driving. (in that order). I think we could have done more at the limit with street tires. Those Kumho's gave so much grip that harder to detect errors and get to the limits at all.

I also completed some data on R-tires at the track
All is for my 944-spec car. 130 or so rwhp, 2450 lbs, 225/50 R 15 all 4 corners. Track only use. (Note 1 heat cycle = 1 track session)

Set 1
Kumho Victoracers
Months used = 1.5
Track Heat Cycles = 6 (very abrasive track)
Approx Track Days (4 sessions per day) = 1.5
Autocross Days = 13
End Reason = Corded

Set 2
Kumho Victoracers
Months used = 5
Track Heat Cycles = 19
Approx Track Days (4 sessions per day) = 4.75
Autocross Days = 4
End Reason = Corded

Set 3
Kumho Victoracrers
Months used = 5
Track Heat Cycles = 20
Approx Track Days (4 sessions per day) = 5
Autocross Days = 6
End Reason = Corded

Set 4
Kumho Victoracers
Months Used = 6
Track Heat Cycles = 10 + 4 races (14 total)
Approx Track Days (4 sessions per day) = 3.5
Autocross Days = 4
End Reason = Corded

Set 5
Kumho Victoracers
Months Used = 1
Track Heact Cycles = 11 + 4 races (15 total)
Approx Track Days (4 sessions per day) = 3.75
Autocross Days = 0
End Reason = Corderd

Set 6
Toyo Proxes RA-1
Months Used = 8
Track Heat Cycles = 35 + 13 Races (48 Total)
Approx Track Days (4 sessions per day) = 12
Autocross Days = 0
End Reason = Lost Grip - Cycled out

Set 7
Toyo Proxes RA-1 - On Track heat cycled
Months Used = 12
Track Heat Cycles = 27 + 12 Races (39 Total)
Approx Track Days (4 sessions per day) = 9.75
Autocross Days = 0
End Reason = Lost Grip - Cycled out - Minor cord

Set 8 - Still Using these tires
Toyo Proxes RA-1 - On track heat Cycled - Shaved to 4/32 from 8/32
Months used = 5+ (on going)
Track Heat Cycles = 11 + 8 Races (19 total) Still good
Approx Track Days (4 sessions per day) = 4.75+
Autocross days = 0

Matt H

M758 - that is really good info, thanks for posting it.
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Brian Morris

M758 - were both the Kumhos and Toyos shaved?

--Brian Morris
89 951

M758

Only set 8 of the toyo's were shaved. Since I have not worn them down I am not sure how it impact tire life. I never hand any chunking issues with any of my 7 other sets of tires however.

Fishey

I think a Dunlop SP5000 sport is a great tire for both if you have a set you will notice they produce great grip and wear and also hold up to abuse amazeingly well..

Riff

M758,

Thanks for the info on tire life. Do you have the corresponding data for lap times? Any correlation between tire life and lap time? Your use of the RA-1 seems to be dictated by lap time, not tire life. How drastic was the fall off?

Thanks,

Matt H

I believe his use of the Toyo to be due to the fact that it is the spec tire for the 944 spec series :>)
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Riff

Ah, spec tires...Duly noted...But he still changed them out BEFORE they were showing cords, whereas the Kumhos lasted until the cord was showing.

M758

Matt, you are right Toyo's are the spec tire for 944-spec.

That said I think they are great spec tire.

I think the Kumho's are a little quicker. I personally have gotten much faster on Toyo's than on Kumho's, but that is driver not the tires. I have seem some guys with a 2 second difference in lap times between toyo's and Kumhos (Toyo's slower). This was for approx 2 min lap. I have also heard that toyo's are almost as fast as hoosiers. Now these are faster than kumho.

So, I do think the Kumho's are a little faster for a lap or two, but I have heard they can go "off" during a run. This weekend I raced with some guys on Kumho's. I won both races, but another guy on Kumho had fast lap in qualfying by 0.06 sec and in the sprint race by 0.7 sec. I had faster lap in the short 60 min endro by 0.6 sec. This was for 1.15 or so laps. So how much slower are they toyo's? Well really hard to say for sure. I can say they last longer however.

THe Kumho's I ran all corded on one or multilple tires in the set. Their grip was ok until I hit cord.

My Toyo's started off a little slick. Once you get a few (5 or so) heat cycles into them they start to grip well. They then last forever. They will look worn down, but never hit cord. In fact I set my fastest ever laps at Arizona Motorsports Park and Phoenix International Raceway on Set 7 of my Toyos with 34 and 38 heat cycles on them. I could tell they were going since the grip curve felt very narrow. If you hit it just right they were awesome, but a little off the mark and slide city. Well by by the 39th they just did not want to stick anymore. I ran that race with all kinds of wheel spin. I could not even get all my 131 rwhp to the ground. I did find one tire with a minor bit of cord on the outside edge. My set 6 was similar. Very fast and then just lost grip on 48th heat cycle. Car was all over the place so I retired them. I probably could have gotten more sessions from them, but it is hard when you feel like you are 1-2 seconds off your normal pace. I have gotten my money's worth from them so I am ok will tossing them. When I put my set 8 on they felt like they had a nice wide grip curve so that you did not need to be quite as precise and were still fast.

The very fastet Toyo's (faster by may be 0.1 sec) are those just about ready to give up. Only issue that grip peak is very narrow and slowly narrows to the point where it is gone and you are off by 1-2 seconds.

Z-man

If I may echo what folks like M578 and ninefiveone have been saying:

Get a good high performance street tire to learn on first. Progressing to R-compounds too early can prevent a 'learning curve' problem.

For example: street tires start 'slipping' sooner than r-compounds. When learning basic vehicle dynamics like understeer and oversteer, it is better to learn these at slower speeds. Also: there are some r-compounds out there that offer so much grip, the newbie track driver will never really experience a noticable amount of understeer/oversteer, since he is driving below the limit of the tires.

IMHO, in terms of DE experience: wait until you have progressed up into a non-instructed group before you start using R-compounds. I waited until I got into the white run group (our classification is: Beginner-Green/Yellow, Intermediate:Blue - White, Advanced: Black - Red) Side note: even when you've reach the non-instructed group, be sure to get instruction as often as you can!

-Z-man.

Danno

I guess that means no to re-treads then, eh???

My 1st couple seasons at the track, I actually used super-hard, treadwear-340+ all-weather M+S tires (yes, they lasted two years with street and track driving). You may have noticed that Paul Mumford won the 2002 OTC on M+S tires as well, beating up on all the other cars with R-compound and SLICKS!

I think starting out on non-grippy street tires makes more sense. The more progressive breakaway characteristics allow a person to learn to feel the car and its limits easier. Much more forgiving when it lets go, gives you time to catch slides, drifting is a lot easier, etc. I've also seen way too many beginners come out on the stickiest tire they can find with an "I'm gonna WIN" attitude and getting into trouble: