Well I had 235's on my '93 Cummins and got 70,000 out of the front. The 245's on my 98 run about 60,000 but its about a thousand pounds heavier.
I just put 2 michelin 245's on from Costco, $137 mounted and balanced. Then I had Walmart warranty a michelin 245 last week and their price was $140 mounted and balanced. The tire had 25,000 on it and bless them, they didn't charge me a cent.
I don't rotate my tires.