Tires :: Rims Suddenly Going Bad

I bought a set of new tires for my 2000 astro van and 1994 Saturn SL2 ::edit:: two summers ago. I bought a "full warranty" with the tires which includes checking the air pressure and free rotation. It seems every time I take the either vehicle back for a tire rotation there is a problem which is not covered by the warranty. For example I was told that each vehicle now has a rim/wheel which is slightly out of round with the implication that this negates any warranty on the tire.

I looked at the tire on my van as the tech spun it around while dismounted as you would a bicycle tire and sure enough the tire "wobbled" a tiny bit when viewed straight on at the treads - like a spoked bike tire would if it needed "truing". I was given a speech about "driving to hot" with steel rims and alloy rims were better as they tolerate heat better, also they mentioned the weight of tools in my van but I pointed out that any two of their hefty employees weighed much more than anything I ever carried in my van. The implication again is that this could negate the tire warranty.

I have driven since the 1960's and this is the first time I have ever had a problem with rims - even through minor accidents. The most I have done with these wheels is to bump them on a curb in a parking lot occasionally.