I recently bought an '05 GT Roadster and have noticed an issue at "higher" speeds. Anytime I hit about 70mph I can feel a vibration/rumbling. It starts very gradually and gets worse as I hit 70 or so. You can feel it in your seat and a little in the steering wheel.

A few years ago I had an '01 Mustang that had a similar problem and it turned out I had a bad rear tire. The steel belt was coming out and as my speed increased the belt got out of round and "thumped" creating the vibration issue. I found out the cause by feeling the inside edge of the tire and I could actually feel the belt protruding with an extremely sharp edge.

This situation feels VERY similar to my Mustang tire issue except I have checked the tires and not found anything protruding. The tires are Federal SS 595's. Not what I would have chosen but they were on the car when I bought it and I've found they are actually pretty good in the rain so I'm leaving them on until spring.

I don't think the tires are the problem. Has anyone else had a similar issue? Anyone have any ideas on what it might be?

Thanks!

 

It could be an unbalanced tire that has not been ongoing long enough to effect thread pattern on your tire yet. Hence, you not seeing any uneven wear yet. Just a thought...

 

+1 sounds like you need to balance your tires.

gl

 

Even though you are skeptical, I'm going to agree. get them balanced or new tires. Had the same problem before on a couple different cars/occasions

 

I would also check to make sure the wheels are mounted correctly. Check the lugnuts, some might not be tight.

You didn't mention if you had aftermarket wheels, and I assume you don't. However, if you do, make sure the hubcentric ring adapter for the wheel is properly seated.

 

+1. These are also good things to check out.

 

Thanks guys I'll take it in this weekend to have them balanced and go from there. (Stock wheels btw.)

 

I had the same problem, but the shaking would start at 80 MPH. Took it to the dealer for 4-wheel rebalance. They acually documented that the right rear tire was in fact out of balance.

All is good now!

Let us know how it goes for you.