Bill.Satellite wrote:
The Firestone tires (12R 22.5) on my coach lasted 80,000 miles and I was very pleased with that. You say yours are only 4 years old and have 90,000 miles miles on them. That's even better. If you still have what is considered a safe amount of tread (Lincon's head is fully visible when inserting a penny into the tread) there is no reason to replace your tires.
I'm thinking you mean Lincoln's head
is not fully visible. If his head is fully visible when you insert a penny in the tread, you have insufficient tread depth.