Help with wheel balance
 

I recently had "new" tires mounted and balanced to replace my snow tires. I say "new" because they are stock 19" pirelli take-offs (less than 8k miles on them) that I got in a package deal with the snow tires/rims. So I had them mounted and balanced in a local shop and have been driving on them for a bit.

I am having a couple concerns - I'm running on 40 psi, is this a good pressure? Also, there does seem to be a bit of a "washboardy" feel when I am going 85-90 mph (not that I routinely do this, but every now and again :) ). It's not a very rough vibration/rumble, I feel it more in the seat than in the steering wheel. And nearly not noticeable at all around normal highway speeds. I don't remember this feeling from last summer when I would reach those speeds. Since I just made the switch, could this be attributed to feeling the road more with the all seasons than with the snow tires? Or even partly due to running the pressure a little on the high side?

I'm almost sure it's nothing but I wanted to be sure. Any experts out there that can chime in are appreciated.

Bump for some input?

Why is your pressure so high?? Any reasoning??

Your psi could have something to do with it. You should be running them around 35 psi, not 40.

My guess is that those tires are more used than you thought. uneven wear in the rear tires would discribe this feeling.

Judging by what I read, it looks like a combination of different tires (snow tires have different rubber compound than summer or all seasons), 40 psi in the tires which can give you a little bit stiffer ride than the recommended 36 psi, and my final opinion is the tires may be mounted on the wheels to where the high spot in the tire may need to be moved to receive a smoother ride. You can ask the shop to see if they "Road Forced" the tires when they balanced them. Road forcing simulates driving conditions and helps insure the best possible balance of the tires. If the road force is higher than what is recommended for a smooth ride then the machine will instruct the operator to spin the tire on the wheel to move its high spot. I hope this makes sense and is of help :)

Awesome! You guys were all a great help, thank you! I'll see if I can find out about the road force. I did lower the pressure and maybe it feels better now? Not sure if I'm just being nitpicky ...
To go along with the different feel of the tires, I did rent a brand new Chrysler 300c for about a week literally right before I took off the snow tires.