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Ok fellow track enthusiasts and those with more knowledge than myself, can you help me understand what is happening with my track tires. I think I know, but I want to sanity check this with those with more experience than myself. After a hard weekend of driving the tires on the right hand side of my car have more wear on the outer shoulders than the tires on the left hand side of the car. I think some of this is to be expected because we are running the course counter-clockwise and have more left turns than right turns.
Additionally, the wear across the surface of the tires looks like this (exaggerated below)
Inside |\|\|\|\|\ Outside
Meaning that the tires are wearing more on the outer edges than the inner edges. I *think* this is caused by a lack of negative camber as I played with tire pressures during the weekend and honestly didn't have a whole lot of variance when reaching speeds at the edge and beyond. I started with 32 front 37 front COLD which ended up as 40/45 HOT. I ended with 35/40 HOT pressures, but again the car was remarkably grippy regardless of tire pressures, but did seem to lose a little grip at the edge when I lowered the pressures. Temperatures across the face of the tire were remarkably even though using Joe's temp tool, we measured around 160 degrees on the front tires as I recall after coming off course and going into the paddock which takes a minute or two to do before we actually put the gauge onto the tire.
Any thoughts? Comments? Suggestions? Recommendations?
This is primarily due to running the course counter-clock wise and lack of camber and probably a little more pressure would be good; however, I have never run MPSC tires, so I am sure.
Watching only the video and not sitting next to you, it seemed to me thatyou were loading fronts a little too much with minimal throttle steer especially on the two of the large radius left and then right turns.
The rears were the same way, and I was actually throttle steering through the carousel (big left hander) but more so when my tire pressures were higher, found it harder to do as I reduced pressures. The right hand turn after that I kept trying to find my best line, I hit it once, then had problems finding it again, I actually think going a little wide of the apex worked better for maintaining speed in that corner but I need more seat time and practice to be certain. Thanks for the reply, much appreciated! I'm assuming some more camber will help, but then don't I start down that slippery slope of more mods to the car? [img]/fckeditor/editor/images/smiley/MWPX/tounge_smile.gif[/img][img]/fckeditor/editor/images/smiley/MWPX/angel_smile.gif[/img]
I had the same experience as Ken. The high speed turns are all to the left. I had several people at the track look at my KUMHO 700's and they felt more negative camber would help with outside wear on R front. The L front was ok and the rears were pretty good. I was running 30fr and 35 rear cold pressure. Ken was running a lot faster than me by several seconds/lap.
Can you post a pic of your right side tires? Were you running MPSCs? If yes, those pressures, 35/40 hot seem a bit high, especially in the rear. On my Turbo I run 34/36PSI hot on the MPSCs. I'd run them a bit closer; given you have stock camber, you want to the front and rear to be closer together. Also, your tire temps seem way low; what was the ambient temp?
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97 Turbo | 06 Boxster S | 06 Cayman S (sold)
I will take some pics of the right side tires, they are MPSC's. As for the tire temps the ambient temperature was between 75-80 when those temps were measured and it does take a bit of time to get back up into the paddock so by the the time Joe got out his device to measure the temps they did have some time to cool down from actually being driven hard, 3-5 minutes maybe? I didn't time it. So your suggestion would be to go even lower with pressures.
32/36 seemed to be the ticket for mpsc's thelast time I was out on a hot day. That tire wear is common, the outside edges of each tread block get eaten away while the inside edges seem to raise a bit from the surface.
Start your track day with 34# all around cold. After your first run bleed them to 40# hot (or manufacturers recomendation, the new R6 Hoosiers are set to 35#) this will provide you with the best all round wear and grip for the track you are running. The next morning measure the cold pressures, this will give you an idea of where to set your car for that track and your driving style. You will find that all four may be at different pressures cold, this is normal.
You will either wear the inside or the outside of your tires first, it doesn't matter what tire you use. We run a lot of negative camber on the MantisSport Cayman and find that we wear the inside rear first. We could reduce the camber to gain tire wear, this would be at the expense of lap time though.
You can extend the wear on your tires by remounting them inside out every few events, just turn them around on the rims. this costs a bit extra but will extend the life of the tires as a result. It is also a good idea to run the rights on the left at the next event, one side is always going to be worked harder than the other.
Ken
Looks like you had a lot of fun. Your pressures seem too high. Although my MPSC experience is on a 993, FWIW I ran at HOT pressures of 33-34. I would think the Cayman should be about the same hot although cold F-R delta would be less (or maybe zero). I found the tires got slippery at higher pressures.
BTW, Michelin's recommended pressures for a 911 are: 25-28psi cold (front / rear), with a hot target of 32-36 (front / rear) with [/quote]target temps for dry track conditions between 160 - 220 degrees F.[/quote]<br style="font-family: arial;" /><br style="font-family: arial;" />Did you measure temps w/a tire pyrometer (sensor pushed into the tire tread) or a surface pyrometer?[/quote][/quote]
I concur I will try even lower pressures the next time out. The sensor Joe used had a pin on the end which was pressed down into the tire tread. You are correct it was a blast, how come you didn't come join us??? [img]/fckeditor/editor/images/smiley/MWPX/tounge_smile.gif[/img]
Could everyone just clarify what tyres and wheel sizes they are using, when quoting tyre pressures.
K-Man S - it looks like you are running standard 18' wheels, but what size Pilot Sport Cups are you using (particularly on the rears)?
MantisSport - I'm surprised you run the fronts at 40psi hot - that seems quite high. I got a lot of wear at the centre of the tread when I let front pressures go above 37-38psi. Recently I've been running around 35psi hot on the fronts.
