tire cupping
 

My dealer stated I have minor tire cupping; what should I focus on first [i.e. what is the most likely cause(s)]; the boxster has 25K miles on it [1999]

thanks

I've always attributed tire cupping to worn shocks.

Hi,

Cupping is usually caused by one or more of several factors such as: An unbalanced tire, faulty wheel bearings, loose suspension parts, fatigued or worn springs or shock absorbers.

Diagonal scuffing and cupping across the tread face on rear tires indicates possible problems with toe. Diagonal tread wear on rear tires is caused when the direction the vehicle's wheels are pointing are not in line with the geometric center line of the vehicle. When this occurs, front-wheel steering can be affected and lead to tire slip or loss of traction or control. The wear pattern that develops on rear tires from improper toe will vary depending on tread design. Wear patterns from rear-wheel misalignment may resemble cupping on tires with performance tread design and diagonal scuffing on tires with an all season tread pattern.

I would start by looking for Tire imbalance. Have the Tires Dynamically or Road Balanced using a Hunter 97XX machine. In spect the Shocks for leaks and problems with rebound (press and release car and motion should stop within 2.5 cycles). Get a realignment from a pro like a Race Shop, not some Tire Store paying particular attention to the Toe settings. Assuming the Tires are OEM, they're shortly due for replacement (as much for age as wear), so saving them may not be possible. But, be sure to do these adjustments/checks before installing a new set of fre$h rubber. Hope this helps...

Happy Motoring!... Jim'99

It's good to catch this sort of thing early.

Absent tire imbalance and worn suspension
parts (which you should notice while driving
it) I would suspect alignment.

MNBoxster gave you some great pointers.

I think I should point out however that in this
statement:

"But, be sure to do these adjustments/checks before
installing a new set of fre$h rubber. Hope this helps..."

MN, I am sure, meant for you to check everything,
get new tires and then get it aligned.

Tires that are worn and cupped will cause different
alignment settings than your new ones. Always
align with the new tires in place.

I am sure that's what he meant to say.

All the best,

- Mark

Tire Cupping
 

I recently purchased a 2003 Boxster with only 5500 miles on it. I had to replace a rear tire thanks to driving it a mile while it was flat (interior tire damage). I took the car to Big O Tires here in Palm Desert, and I was told that the tires were cupping and that the car would need an alignment. I think I'm going to buy another new rear tire so I have both tires new in the rear. When I took my car to the dealer, he told me that my car didn't need an alignment, and that the tiptronic trans was heavy and it made my car 'squat' more, which can lead to inner tire wear, or cupping. The service manager told me to monitor tire air pressure and keep driving it. So the question is, do I need an alignment, do the tires/wheels need to be balanced...or what? I don't want to spend unneccesary money on my vehicle, however I don't want to wear out my tires ever 8,000 miles as my Porsche rep said they would...please help.

Hi,

If your tires are cupping, there is something wrong - Porsche didn't set up the car to cup the tires. Read my earlier post and go from there. Your tires may need balancing and you may need an alignment. Alignment, contrary to most's thinking, isn't mileage related - example: Get your car aligned, leave the Alignment Shop, hit a giant pothole or a curb stop, and BOOM - you need another alignment. Yes, with alloy suspension parts, it is that sensitive.

Most people require an alignment annually, though few get one. Instead, they live with vibration, steering issues, accelerated Tire wear, possibly even safety issues, all of which cost them an equal or greater amount of money in the long run than regular alignments would. It's a Sports Car folks, and a Porsche at that... you gotta Pay-to-Play, don't like it? Buy a Honda!...

Happy Motoring!... Jim'99

HAHAHAHA I like that!