Strange Handling

2002 C2. Replaced shocks and springs in June with Tire Rack Koni kit. What an improvement! Immediately went on 1,500 trip, with no issues. Didn't get an alignment at the time because I wanted to wait until I replaced the tires. Got new Sumi's last month (on my third set) with alignment, but didn't drive it much until this past week. (Sway bar bushings previously replaced.) Drove to see a friend about 120 miles away on Thursday, mostly interstate, without issue. However, returning yesterday I had an unsettling experience. Halfway home I encountered about 15 miles of rebuilt interstate. Not just resurfaced, but brand new concrete in both lanes. I pretty quickly realized my car was rockin' and Rollin', and not in a good way. I passed an RV who looked like he had his hands full too, and at first I thought it was just windy. But no, it seemed to be the road surface. I was going 79 mph, but had to slow down to under 70 to feel in control. Thought maybe I was getting a flat, but when I pulled over to check, they were all fully inflated per my tire guage. Got back on the road, and when the surface returned to smooth tar the car handled just fine. My buddy did me a favor last month and took my car to a shop 30 miles away that aligns a lot of Porsches. I asked for a stock street set up. I once had an aggressive alignment on a Miata, and while tons of fun in the twisties, I tired of the constant corrections needed at highway speeds. This doesn't feel remotely like that. Not sure if my alignment is the culprit, but I've got to address this. Other cars were blowing by me while I had my hands full at 70 mph, so it can't all be blamed on the road. Haven't had a chance to get under it and check everything. Any ideas?

I had this same thing happen to me with new tires on a new road surface on a 2002 BMW 325CI. What was happening is that the road surface grooves were parallel to the tire grooves, and because the tires were new, they had the most depth possible. That�s not enough to cause the problem, though. What causes the problem is the spacing correlation of the grooves being in line with each other. So the tire actually sits inside the grooves like record needle on an album. It causes the car to move back and forth since the grooves are not usually perfectly straight. I suspect some tires and roads are worse than others. It will go away eventually when the tires break in and wear, and also when the road breaks in - those grooves start to smooth out.

Wow, you may have something there. Much of the concrete was etched, for draining purposes when it rains hard. I've never felt anything like it before. Thanks! I think I feel a little better.

I was thinking the same. I agree that the etching could be the issue if it was present. I am a motorcyclist and that type of road surface should be banned.... Very nasty on a motorcycle. Some DOT's are using this on curves but surprising that it would be on a straight section of road.

I notice this as well when I switch to my snow tires. Softer rubber and on some roads the car tracks really odd, others no issue at all.

Quotes source post: 14644804

it�s called �tramlining� your tires get aligned to the rain scoring in the highway like tram wheels in a track

There is a 30 some mile section of road here with concrete sections and grooved. Car is a bear to hold in a straight line in the lane @65mph, just wanders all over the place and requires a lot of concentration. On all other roads the car is perfect and tracks like a train on rails. Chalk it up to the cruddy road surface. I avoid that road.

You guys have made me feel much better!

http://www.dot.state.mn.us/research/...0/201040TS.pdf Pretty good article on pavement grooving. It was discovered if the grooves go with flow vs perpendicular (old way) it reduces tire noise by 4db. I notice very different characteristics in the way my 996 feels vs my SUV on a new road near me.

Had a similar experience with my '02 C2 Cab, but it was white knuckles all the way home from shop. I was scared as the car was upset over the slightest bump and would go in a direction I didn't expect. Had it flat bedded back to the shop. They drove it, and the tech came back white as a sheet. What they found was that one of the eccentric rear control arm adjusters for alignment had become loose, so when I hit a bump the alignment would change! They tightened the adjuster bolt eyeballing it to match the other side. I drove home, and all was fine. Will wait until spring and then get the rear suspension dealt with and an alignment. At least the car is drivable. That may not be the OP's situation, but I thought I'd share if it helps someone else!

The tracking/tramlining/ditchfinder tendency will also subside as the compound hardens up. On squishy new tires - especially all-season tires - the first few hundred miles can be unsettling (if I read OP correctly, these are still pretty much brand-new tires). I always get a little weirded out after I switch my wife's SUV over from summer tires to all-season tires. They tramline like nobody's business, and the all-temperature compound feels really weird when cornering. Hope the alignment helps!

Yes, these are brandy new tires. Maybe 200-250 miles on them when this occurred. Had the car for 6 years, 70,000 miles and my third set of Sumi's, and I never felt anything like this. But alls good now, so learned something new.

You have a car with one of the best steering there is - it responds to the road surface and gives great feedback. This is one of the prices we pay. Tramlining is the best description. SUV tyres are designed with an entirely different brief