Ok, this may be showing my car ignorance, but lately my car shudders at 45mph exactly. Only when I am accelerating slowly though, not when I pick up speed quickly. Any thoughts on what it is?? Thanks in advance for any thoughts!

 

maybe you shoould see if your tires are out of balance..

 

i live in beaverton and maybe able to do this for free...just let me kno my name is kyle

 

It sounds like your tires are out of balance. Also, you might have a bent rim. Both of my fronts were bent; Replacing them made my ride (especially at 85mph+) smooth as glass!

 

I live in Oly, WA, about 2 hours from Portland/Beaverton I think. How much do tire places usually charge to do this sort of thing? Not that I won't keep ya in mind Kyle, just a long drive.

 

If the car shutters at only 45mph, and it doesn't get worse as you go faster, it has nothing to do with tires/wheels. Balance/run out problems get worse as speed goes up.
It sounds more like an engine "stumble" under load at low RPMs. When you accelerate harder, you're probably in a lower gear, and at a different RPM as you pass 45 mph.

 

You may have a defective tire, with a lump or a "bubble" in the sidewall or the flat surface, I had this problem on 2 sets of rims, on my stock rims, 1 tire had a small, 1-2 inch bubble in the sidewall, it caused vibration you can feel in the steering wheel and gas pedal, it usually was felt around 50mph. On a set of 17's I put a pretty large lump on the inside sidewall and it caused vibration at 50-60 as well....