When to replace tires on 2008 F-450 dually? Age? Tread wear?

6 years old is a conservative limit. I would start looking for a good price next spring. If you have steel sidewalls, get replacements with steel sidewalls. Changing to polyester sidewall tires - you will regret it the first time down a hill, when the trailer is pushing the truck into the corners. The steel sidewall is much stiffer, and I learned the expensive way to get the right tire the second time.

I just made a trip with two front tires that have a date code of 3401. Right rear look the worst with a date code of 1105, that is 8 years old, I know it is way to late to change them, but I had no money, and did make it safely.

The other two tires have a date code around 2207, if I recall right. My spare, I am afrade to look. I think it might be 04 or 06 - but still I will need 7 new tires before another trip. I know these have been on borrowed time, and if gas prices where not so high, I might have wanted to go camping, but lately the RV has stayed parked. Next month it will be parked again for another 6-8 months!

Fred.

I replace mine when they wear out, or get to 7 years old per DOT code.

No tire trouble except a few repairable punctures in over 200,000 miles. Works for us. Not sure if it makes a difference, but we never use Chinese tires.

5 years isn't something I'd be concerned with.

I should note that tires are dated 10th week of 2008.