I bought a set of Avon Tech R's for my 928 last season (225 50ZR 16). After the initial few autocrosses, the tires were rotated for each event. Three of the tires look like they'll make it through the second season. The fourth, however is toast - grained, chunking and corded. Judged on my experience with the other three, I suspect this was a defective tire.

The problem is that the Tech R has been replaced with the new Tech RA which, according to the Tire Rack, is incompatable with the original Tech R and should not be mixed on the same car. I haven't found any information as to just what it is that makes them incompatable.

I can't afford to replace all four tires just because one of them is bad. So, I'm leaning towards buying two new Tech RAs and using up my three original Tech Rs. The new pair would be kept on the same axle (either front or rear). I don't time trial the car, just autox.

Any thoughts on miss matched sticky tires? I don't think miss matched Avons would be any worse than mixing Avons with Khumos (for example).

James

 

For autocross there's no magical tire compatibility danger that is going
to cause any spectacular disaster. One tire will stick differently than
another, transition differently etc, but it's not a big deal if you just want
to get around the course. If you buy two new ones, and put them
both on the same end of the car, you should be fine.
Joe Weinstein

 

Joe got it right. In Autocross, I wouldn't be too concerned unless you have really fast courses (80+). If I was in your posisiton, I would by two and put the new ones on the end that wears the most until they are worn to the same amount as the originals, then rotate as normal. Good Luck!

Matt

 

If you have street tires you might want to leave 2 street tires on and put the 2 new AX tires on as well and run them around town to heat them up a few times. This will help to heat cycle them a few times. Best wishes - Jay

 

Thanks for the advice.

Yeah, I heat cycle the tires on the street before I autox them.

My gut instinct was that the "incompatability" between the Tech R & new RA was not going to be a problem on an autox course. Our local course is kind of like a mini time trial course - we even have a bit of elevation change. I run the whole course in 2nd gear and, depending on the course configuration, sometimes run about 300 rpm over redline - which works out to about 70 mph.

I think I'm going to stick to my original plan & have my three good Tech Rs flipped on the rims so that the best rubber is on the outside, buy two new Tech RAs and just use up my Tech Rs. When they're used up I'll buy another pair of RAs.

James