The Kumho tires are quiet but squirmy

[Dale_K]

The 2000 S I recently acquired had 4 fairly new tires - less than 6 months old, but the steering wheel shook and balancing didn't fix it. The left front was cupped moderately on the inside so I decided to replace both fronts, which were directional tires in the Formula 1 rain tire tread pattern. My experience is that those style tires develop uneven wear pretty quickly and they get loud pretty quickly too. So I looked at all 225/40/18 tires at Tire Rack trying to find some asymmetric tires rather than directional tires. At least I would be able to rotate them from side to side to even out the wear and try to keep them from getting nasty loud. This is the tire I picked, a Kuhmo.



The tires are nice and quiet but I've lost some of the steering responsiveness, which is a pretty big deal since the Boxster is about chassis communication. Now the car understeers more than I like. It's almost like I need to get some squirmy tires for the rear to match the front, lol.

What kind of tire pressure adjustments reduce understeer? I'm running 29/36 right now.

[Flavor 987S]

Are the 4 tires matched? Never mix tires on a performance sports car.

How many miles on the new tires? It takes about 200-500 miles to scrub off the mold release tire manufactures use in production, this was covered in the product information you received with the new tires. Did you read it?

I suspect your tire pressures are low. Your cold pressures should be more like 32 front and 36 rear.

Were the tires road forced balanced? Alignment completed?

[Idaho Red Rocket 3]

About a year ago I needed to change the tires that came on the car when I bought it. My tire dealer talked me into Continental DWS. Great traction in all conditions but terrible, I mean terrible for what a Boxster can do. Understeer like crazy and no high speed stability. Fortuneatly they came with a love them or leave them warranty. Well after some intensive on line research, I replaced them after a few months with Kuhmo ASX. Let me tell you about that tire. WOW !!!! They do everything a Boxster can do. Or at least everything I can make a Boxster do. Yes they did have that wiggle squirmy feeling for a short time at first. That went away quickly.

As much as I hate to buy off shore tires ( Go figure that one out. I own 2 Porshes and several motorcycles made off shore.) I realy hate and won't buy Chinese and I'm not to hot about Korean stuff either, but I have to admit the Kuhmo ASX to me is an awsome tire.

[mikefocke]

cupping might have been an alignment issue, did you have that addressed by a Porsche-knowledgeable shop?

[Dale_K]

Haven't done an alignment yet. I have some hope these tires might improve a little as they wear. Skinny tread blocks and full depth tread can create squirm. I think racers shave most of the tread off tires to improve handling.

Still looking for tire pressure advice to reduce understeer.

[Topless]

Ok Dale, we can probably help you sort this out. Start at the beginning. Are these the tires you just put on the front?
http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=Ecsta+LX+Platinum&partnum=245WR7ELX&vehicleSearch=false&fromCompare1=yes

What tires are on the rear (exact make model and size)?

As long as the tires are very similar in type, temperature, traction, and wear ratings, even different brands, they should work together pretty well. If there is a big mismatch in tire compound no amount of air pressure or alignment changes will get them to work well together.