Tire wear Slicks

[yellowss7]

I just got around to cleaning the marbles off my Hoosier slicks from the track day I did at LOG29. I noticed that the wear on the rear tires was pretty even all across both tires. On the fronts, both left and right, I notice that there is no wear on the outside inch of the tire.

 

Any setup experts out there that can tell me if this is normal? I thought that maybe it's just a result of the camber (and my slow driving).

 

Car is set up with a little toe out as well if that has any bearing.

 

Tom

[WestTexasS2K]

It could be several issues.

1. To much camber.

2. Not driving hard enough to get the car to roll on center. If the car is sprung tight or have alot of sway bar it may not roll enough to use the whole tire.

3. To much tire pressure. Usually this will show more wear in the centers and less on the sides.

 

Are you using bias ply slicks or radial? Bias ply slicks dont require as much camber as a radial slick. The side wall stiffness differs greatly between the two.

 

I am far from an expert just a few items I would check. Best way to tell proper alignment is tire temp across the tire with a temp probe about 1/8-3/16 into the tire. Surface reading with a temp gun is very misleading.

[yellowss7]

Thanks for the suggestions. They are Bias Ply Hoosiers. in the R25B compound, their softest. When I autoxed I ran them at 12-12.5 psi all around. Should mention that these are 10inch wide at all four corners.

 

This was a brand new set that has only run 1 track day to date, so the wear is from that event. I did bump up the tire pressure to 16 psi cold for the event and to be honest, never checked it between runs to see what it the Hot psi was.

 

I was certainly tenative on my first few laps but the rest of the days sessions I got it going pretty good. Obviously I wasn't running at 10/10ths or probably not even 8/10ths. Just having fun.

 

Car stuck like glue so no complaints with the set up. (It was done by George Alderman at MidAtlantic Caterham)

 

I can't remember what the settings were, but it doesn't look overcambered compared to other Caterhams I've seen.

 

As for the springing, I have the stock 150lbs front springs and the stock rears as well. I'm running the 19 mm rollbar in front and the rear arb is set to the most forward (stiffest) setting.

[Mondo]

maybe you only need 9in wide front tires;)

[MichaelD]

May be due to negativew camber in the front.

 

Michael D.

 

Hope all else is good.

[WestTexasS2K]

Was the alignment dune with those tires on the car? Was he aware that you were running those slicks. I havent run the bias ply tires before, but I think that the camber should be .5 degrees or less. Radial tire can run over 1 degree.

 

This doesnt mean that the car would handle poorly. It just wears tires faster and the car isnt at its full potential without full rubber contact. I suspect with 10" wide tires it probably does feel stuck like glue. Just imagine if you were using all 10" of the sticky stuff.

[yellowss7]

Good catch West Texas! No the car was set up with the Avon Cr500 radials on. Duh! Not only are the slicks bias ply, but the profile is alot less too.

 

Thanks

 

Tom

[yellowss7]

Hey Michael D. :seeya: Things are great. Let me know next time you're doing a track day. I'll come down to watch. On Saturday I went out to Berks county Pa. where a new Race Track is proposed. Still at least 2 years out but it's only 1 hour from my place and looks like it could be a winner. Tom

[Davemk1]

I run .25* camber on the front of my Birkin with Hoosier slicks and 1/8" toe out for autocross and get pretty darn even temps across the tire. I'm running 8" wide tires with 14 psi FWIW.

 

 

dave

[Boxologist]

Good catch West Texas! No the car was set up with the Avon Cr500 radials on. Duh! Not only are the slicks bias ply, but the profile is alot less too.

 

Thanks

 

Tom

 

If u ddin't have the car re-alligned since the initial one, its probably still the same. There really no room for the allignment to change less u go wild w/ fabrication like Norm B. I think Loren has hit the nail on the head. U not seeing the violen inputs of autoX on these tyres since they've only been to a trackdate so ur not onto the outside edge. I suspect as a track novice 8" up front and 9" in the rear is probably better suited for the inpts that are needed. IIRC ur r888s are closer to those sizes.

 

And if u feel it neccessary. i will wera the outside edges of the r25b for u next season. I should be recieving a set of well used A6s that i will use for a Evo school that u can have afterwards.:drool: