Hombres: I just put almost new (less than 100 miles) wheels and tires from a 2001 996 on my 88 944 Turbo S. They look good and fit good, but now the car follows EVERY groove in the roadway whereas with the previous 16" rims/tires I had no such difficulties. I seem to feel it all through the front tires and on occasion really have to wrestle with the steering wheel to keep things straight. My shop did a thorough alignment with the mounting of the new 18" rims/tires which are Continentals mounted on hollow-spoke Technology rims. The old tires were Dunlop D40's on Design 90 rims. Front tire width remained the same at 225 (225/40/18 vs 225/50/16) and the rears changed from 245/45/16 to 265/35/18. I'm running tire pressures of 35/36. Wondering if any of you have any suggestions or comments.

Thanks,
Pat Kennedy

 

This symptom usually appears when front and rear tires have drastically uneven tread depth. For example, when one gets new rear tires while leaving the fronts half worn or less.

 

Several different things can affect the amount of "tramlining" a car experiences. A lot of people who have never driven a car with wide performance tires are often surprised by the feeling that their car wants to follow every rut in the road. They often react by thinking there is something wrong. In reality, all high-performance tire/wheel setups on performance cars will experience this effect to some extent.

Things that will affect how much it does this include: width of tire, stiffness of tirewall, tire tread patterns and depths, suspension design, wheelbase of car, track width of car, wheel offset and alignment of suspension.

Wheel offsets, especially if they are wrong, can cause this to happen more strongly. Less toe-in in alignment can also increase "tramlining".

If I were you, the first thing I'd check was the wheel offsets of the 996 wheels versus those values for your 944 wheels. They might be completely wrong for a 944.

 

Thanks for your responses. We can safely rule out "drastically uneven tread depths" since as I stated in the original post that all 4 tires have less than 100 miles on them.

As for the offsets, the fronts remained the same at 52mm, and the rears changed from 47mm to 40mm. Nothing drastic there. I'm going to play with tire pressures and some alignment specs to try and affect some changes. Thanks for you insight, Chris.

PK