Kuhmo XS installed! - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Adam · 08-25-2009, 03:58 PM

I finally got rid of my worn out Michelin PS2's and replaced them with these XS tires. These tires are supposed to be the best/fastest of the new crop of high performance street tires so I'm pretty psyched. C&D tested them and they were a full second faster than PS2's on a 1 minute autocross course. Grassroots Motorsports mag also did a comparo and they came out on top. I'm doing a HPDE down at Gateway in STL this Saturday and several autocrosses in the next month so I'm eager to see how they do.

Best part is they cost $773 shipped from Tire Rack in 18" sizes. I'll let you guys know how they compare to the pricier Michelins.

jmatta · 08-25-2009, 06:24 PM

Brand new, your tires have a tread depth of about 9/32nds. I would keep a eye on them if you are doing a high speed track event, as you may chunk them.

Tread depth that deep could cause some real premature wear (that's why they shave new tires for track use).

Let us know how it goes...

RandallNeighbour · 08-25-2009, 07:15 PM

Adam, be sure to come back to this thread and report on how they're wearing, the grip they provide, and of most interest to me, if they "wagon wheel" when cold like the Kuhmo's I had on my boxster after I first purchased it.

Those Kumho's sucked. I swore I'd never buy the brand again, but I'd love you to prove to me I was wrong and I need to eat those words. My wallet would thank you profusely.

Adam · 08-26-2009, 07:17 AM

Quote:

Originally Posted by RandallNeighbour

Adam, be sure to come back to this thread and report on how they're wearing, the grip they provide, and of most interest to me, if they "wagon wheel" when cold like the Kuhmo's I had on my boxster after I first purchased it.

Those Kumho's sucked. I swore I'd never buy the brand again, but I'd love you to prove to me I was wrong and I need to eat those words. My wallet would thank you profusely.

The grip should be exceptionally high. I can already tell taking a few on/off ramps that these things stick very well. Tire Rack indepently tested these tires with a standard BMW 3 and they got 1.02 G's on the skid pad....highest they've ever had with a street tire. With a real sports car like the Boxster I expect that number to be even higher. I've noticed they pick up sand and gravel off the road quite a bit more than the PS2's. Their tread wear rating is 180 compared to 220 on the PS2's so I know they won't last as long. If I get two seasons or 10,000 miles out of them I'll be happy. This tire should be ideal for someone doing weekend autocross/track, but also drives on the street and doesn't want to invest in a trailer, 2nd set of wheels, or new tires every 6 months.

You probably had the old Kuhmo MX tires. Those things weren't all that great and didn't really do anything well, but the price was good. These XS are light years better in the performance dept. By "wagon wheel" are you referring to flat spotting when sitting? I'll note that as well. This XS tire also reportedly doesn't do well in the rain so some people would have to take that into consideration....luckily I don't drive the car much in the rain and I doubt you do down in Houston. Also, you shouldn't drive them in sub freezing temps like most performance tires. I think these tires will wear out too quickly for some, and they're not for everyone, but if your needs are similar to mine then I think you'll be very pleased. I'll report back once I get some more miles on them.

jmatta · 08-26-2009, 07:26 AM

I'll just hope for the best and try to shave them the old fashion way

Just remember to be smooth...the more you attack, they more the tires will slide, causing damage to the tread block. I'll be curious to see what you think as I usually use a DOT R compound tire and don't have a lot of track experience with street tires; only what I witness as an instructor (I've brand new tires gone in one track day!)

ekam · 08-26-2009, 08:29 AM

I see your point but the XS have pretty decent size tread blocks. Not as big as my Star Spec tho...

Adam · 08-26-2009, 09:08 AM

Quote:

Originally Posted by jmatta

I'll just hope for the best and try to shave them the old fashion way

Just remember to be smooth...the more you attack, they more the tires will slide, causing damage to the tread block. I'll be curious to see what you think as I usually use a DOT R compound tire and don't have a lot of track experience with street tires; only what I witness as an instructor (I've brand new tires gone in one track day!)

This is my first HPDE and I have to ride with an instructor so I'll try to just concentrate on smoothness and driving technique. This will hopfully be a better way to break them in over the herky jerky movements and quick transitions of most autocrosses. I'm only going to do one 20 minute lap session and classroom time instead of all day long so I can just get my feet wet. It is only going to cost $55, all day long is $225 and five 20 min sessions. Like Ekam mentioned the tread blocks are on the bigger side and look robust so well see what happens!

Adam · 08-25-2009, 07:16 PM

Quote:

Originally Posted by jmatta

Brand new, your tires have a tread depth of about 9/32nds. I would keep a eye on them if you are doing a high speed track event, as you may chunk them.

Tread depth that deep could cause some real premature wear (that's why they shave new tires for track use).

Let us know how it goes...

Yeah, I know shaving them would be best, but I just can't bring myself to do that. I'll just hope for the best and try to shave them the old fashion way.