Went to Firestone and wanted my tires balanced because minor shake at 60mph. Want to see if balancing will solve the problem. Guy told me to replace all tires instead and they wont balance the tires for some reason.
Also, I heard that its not good to have uneven tires and will cause problems to the transmission or differential. Isnt that is why its a differential? Also, its only between 1/8 to 3/16th of a difference. I'm confused. Tire pressure on the door for front and rear is over 10psi difference. What if you did not notice that one of your tires is much under pressure than the rest? I cant get all 4 tires right now and Firestone told me that it cant be balanced.

 

that small a tire difference will not matter,
where it comes into play is if you have old worn tires and try to throw a new one on.
the other problem is people do not work there spare tire into the rotation,
and they have 4 worn tire and a brand new spare.
have someone else try and balance it,
most local gas station can balance tires.

 

Any tire can be balanced as long as the treadwear on that tire is even. If a tire has a flat spot that is 1/8-3/16" lower than the rest of that tire, then balancing will not stop the thumping/shaking.

Get a tread depth gauge and measure your tire in seven different spots around the circumference and make sure they're not flat-spotted.

If your tires are even within themselves, but have varying amounts of tread depth one to another, then just take the tires to another shop and have them balance them. If you have to, take them two at a time.

I've never had a shop refuse to balance even flat-spotted tires, much less unevenly worn tires, or damaged tires. They just do it, and will tell me, "we balanced the tire, but look, this is why it will still shake."