I tire tested this last Time Trial at Buttonwillow. I'm running 23x9x15 canti slicks in the following:

Goodyear = R430 Compound
Hoosier = R60 Compound

I scubbed both new sets of tires in 1 month ago at Laguna. I then ran the Goodyears in session 1 on Sat and Hoosiers in session 2. I reversed the order on Sunday in order to be fair about track temps. Both days were low 80's ambient.

Saturday I was 1.8 seconds a lap quicker with the Hoosiers and Sunday I was 2.2 seconds quicker. I guess all it means is that the Hoosier compound was working better for me that weekend.

Does anyone know if Hoosier and/or Goodyear changed their rubber formula significantly over the last year? Last season the tires performed nearly identical.

Anyone with similar experiences?

Bill P.

Since I am slickless....unslick?... I hab no answers
for you, only questions. While I was pondering slicks, I noticed Hoosier's softest compound for the Cantis was R45. Do you use those for AX....or whut?

I just may attack my fenders before the season is over.

Goodyear did change their rubber compund on many of their tires this winter, including the 9x23x15 slicks. It caused a delay in shipping from south america or where they are made. I got a set at the HSR race in Phoenix and they were the old compound so I have not had a chance to see the difference is. I can't remember which compound number is which, is the R430 the soft or medium? I use the soft compound and it does take a lap or two for them to get full grip as opposed to some tire such as Victoracers which a good on the first lap.

Hi JP and John,

I run R45's for Auto-x and for tracks easy on tires like Laguna Seca and I run the R60's (it's now R55's I believe) for the tracks that are tougher on tires.

The tire compounds go something like this for the canti slicks:

Softer to Harder
--------------------
210 Goodyear (No longer available)
R35 Hoosier
250 Goodyear (Newest offering, replacement for 210)
R45 Hoosier
430 Goodyear (Most common Road Racing compound for folks partial to Goodyear)
R55/R60 Hoosier (Most common Road Racing compound for folks partial to Hoosiers)
600 Goodyear

I've used the 210 and a now discontinued 270 Goodyear compound for auto-x and the R45 Hoosier compound for auto-x. The 210 Goodyear's were definitely the stickiest but are no longer available. I don't feel any difference between the R45 Hoosiers or any of the other Goodyear compounds other than I have observed that the Hoosier seem to wear a little better than the Goodyears. Also the Goodyears have a much stiffer sidewall, so turn in is quicker on an auto-x course. On the track for whatever reason the Hoosiers and Goodyears feel the same for steering input.

The R45's heat up in 1 lap on the track. The R60's heat up in 1 lap as well, but I also help scrub them to temp during the warm up.

Lots of data......

I'm keeping track of heat cycles on each set. I'll report back with how many heat cycles you get before the tires go off pace.

Thanks,

Bill

Is a race slick softer than a DOT autox tire like a Kumho? Anyone know?

The autox tire is made to heat up quick but how do they compare?

OK the slick has more contact with the road but if you look a the specs of each tire they are about the same width.

Paul

I tried slicks a couple of times in the past. Back when you could buy slightly used slicks with some life left in them. I was disappointed to say the least. The grip was tremendous and they wore fairly well, but the damn things simply did not hold air. if the sidewalls were wet, you could see the tires leak right out the sidewalls (many tiny bubbles would appear). This was true of both sets of goodyear slicks that I tried. Granted, this was many years ago and the slicks were not the radial slicks, but I went back to the DOT tires of the time CompTA R1's. I do miss those. That was back before they wrecked the tire and created the "groove of doom" tires.

Do the slicks nowdays still leak air like seives?

the set i bought a couple of years ago are still holding pressure pretty well. (that'll change pretty soon, as i think they're going on the 911 for an event to try to use up the last of the rubber to try to recover a little of my investment...)

there's no reason for slicks to hold air for a long time.

in racing applications, they're on the track for somewhere between 30 minutes and 50 miles. on the AX course they're on-track a couple of minutes. in that application, rubber in the sidewalls just adds weight.

they're not designed for street use, and you expect to have to adjust the pressure before every track outing anyway...

Goodyear slicks hold air overnight....Hoosiers leak like a sieve and will be flat in the morning.....when heated up during the day they don' leak....only after cooling off. Don't trailer the car on the Hoosiers....switch to your rollers before loading...

Bill P.