911sport

I just put Kumho all-season ASX 18" tires on my 03 Boxster, replacing Pirelli Rosso summer tires. In the first 100 miles or so, the Kumhos give a stiffer ride(expected) and the rears seem a bit noisy on hitting the gas--almost as though there was a hole in the muffler(can't believe that). The Rossos seem a good deal quieter, though the Kumhos have a lower noise rating on Tirerack. I'm not getting much noise in the steering, just the rear. And it's a bit worse at higher speeds.
Gas mileage is down about 10% from the Rossos, and there is a bit of drift to the right on a level road--at times.
I don't know if these tires were spin-balanced when installed at the dealers, but there seems to be more noise than what I experienced with the Rossos. The Rossos give a splushy ride ( a bit too splushy), and tend to flat spot the first few miles driving. But they seemed to be quieter and gave better gas mileage based on a few fillups.
Any experiences ?

Devildog2067

I've been running ASX's for a year now and have had no problems. Road noise was comparable to the Michelin Pilot Sports they replaced. Warm weather grip was pretty close IMO, although I don't push the car all that hard. I did give up about 1% in gas mileage and I think the sidewall is a bit softer; I get more body roll than I used to.

I did not experience anything like a drift to one side after having the tires installed. That sounds like someone at the tire shop knocked something out of alignment to me.

Overall I love the tires. They were half the price of the Pilot Sport all-weather tires, and with the kind of driving I do (spirited, but still just home-office-home commuting) they deliver all the performance I need without the need for a dedicated set of winter wheels and tires.

911sport

I noticed today some greasy black stuff on the four fenders around the tire well. I've never seen that before with a new tire, including the same Kumhos I put on my SC. Can this be rubber curing and molding agents coming out of the tire? I know this comes out of a new tire, but I've never seen it collect around the tire well. Beginning to think there is a problem.

nickg

i just installed these tires, get a 4 wheel alignment. mine are greatr, i love them, but i JUST had an alignment

911sport

The dealer said the residue was some kind of new tire coating. There is a drift to the right, and this can be corrected by switching the front tires. Common for assymetrics. I'm hearing some further noise (vibration?) in the rear on accelerating, but the mechanic said it sounded normal to him.
We'll try switching the front tires. Gas mileage, by the way, is OK, and a bit higher than the Rossos. I've seen 31.8 mpg on the highway with the on-board computer vs about 29.4 max with the Rossos.The stiffer matrix of the all-season tire should reduce rolling resistance.