Originally Posted by krazyking
What do you mean by 'they were out of round'? The guy at the garage this morning mounted and balanced my new tire but said he couldn't balance it properly because it was too heavy?? He then said if I had any vibration I should come back. After driving on the new tires for 10 mins, the vibration was 10 times worse than it was earlier... FML
By 'out of round' I mean that there was a high spot in the tire itself. Either that, or some form of non-uniformity in the sidewall and/or footprint in the tire itself was causing it to not roll perfectly round when compressed/loaded under weight. In my experience, if there is more than 0.010" (or about 10 lbs of road force) of loaded runout in the tire, it WILL cause a hop/vibration in the tire itself. It's very similar when it comes to 'warped" brake rotors; if there is a large enough variation of lateral runout on the rotor itself, you'll get pulsing/vibration in the brake pedal. Same applies to tires.
What kind of machine is your shop using to balance the tires? by "too heavy" was your installer referring to a high road force reading? I'd try and find a shop that has a Hunter GSP9700 and ACTUALLY KNOWS HOW TO USE IT!!!
Here's some info on what, more than likely, is causing your vibration:
Here's a store locator for finding a shop that owns the balancer I suggested: