Sinking Creek 4WD Association

Ok, I have a problem.
I traded some things to get my hands on some nice, hardly worn 33x12.5 tires. They look great....untill you look really close. They have some surface cracking from were the guy had the jeep parked in a shed for 2 years. They still hold air and the cracks just look to be surface cracking, except for one that has some cracks at the base of the tread about 1/16 - 1/8th inch deep (depends on how you measure).
My question is, are these tires safe to run? I want to make sure they don't blow up as I drive down the road. I am thinking about running them on the jeep if they are safe. I was also thinking about taking the one that looks the best and use it as a spare and just by 4 new 33's. The tires are "D" rated and look very beefy.
Let me know what ya'll think.
Todd

I've had two sets of dry-rot tires, one extremely dry-rot set that were like 10-15 years old, and my most recent ones seem a bit dry-rot, I didn't have any problems but disclaimer yada yada bullshit.

you should be fine

The tires on my new truck are already starting to crack after 5 months and 3700 miles. Run the piss outta them.

Cool, I think they will work. Thanks for the input. See ya'll on the trail....