I have a 2002 Subaru Forester with 201,000 miles, it runs great. However, I just put new tires on and I have terrible shaking in both the steering wheel and the seat that was not there prior to the tire change. I went and had them balanced and the mechanic suggested it was maybe a mechanical problem because there is still some shaking. This shaking is also very pronounced when I hit the the brakes but I am pretty sure the brakes are fine because I changed the the entire front brakes, calipers included and the rears last spring. Again, this car is pretty high in mileage and I am pretty sure much of the front end is stock from the factory. Any ideas???
If it started shaking immediately after getting the new tires, then I suspect that either the tires themselves have a defect such as misaligned belts or one or more rims got bent while dismounting the tires from the rims.
The first thing to try is to move the front wheels to the rear and the rear wheels to the front.
I agree with keith that it is likely tires - and probably out of round tires.
But hitting the brakes shouldn’t change anything if it is strictly tires. So maybe there is more than one thing going on. Lug nuts torqued too tight?
So go back to where you bought the tires and explain the situation. First, it is possible the tires are flatspotting - a temporary condition due to sitting for a while in one place - like overnight. This should work its way out in a few miles.
It is also possible the tires are out of round - and to diagnose that the shop needs a Hunter GSP9700 RoadForce Balancer. Ask if they have one.
Oh, and we are talking about changing 4 tires, right? Changing only 2 could cause the center coupling to react the way described due to diameter differences.
" Changing only 2 could cause the center coupling to react the way described due to diameter differences. "
Excellent point, CapriRacer!
A brake caliper can be dragging(occasionally) causing your vibration. If you feel near either front wheel after driving is it really hot?
My wife’s Subaru with <2 year old reman calipers had the same issue. The heat was very pronounced in one of the front wheels.
But like others stated rotate wheels front/back to test and see if vibration level changes first.