'41 Ford COE questions

[cwh]

Originally Posted by Ol' Ron

Do a compression test on the engine.

Pardon my inexperience but why a compression test? The truck runs really really well. Almost no smoke at all anymore.

On another note, tires are becoming a challenge to locate. I've found a pair of 7.50x20's but need 4 more. I'd like to buy a matching set of 6. I'll probably have to order them. Are bias ply tires the only tires that'll mount on the old split rims? None of the tire shops here in AK suggest anything but bias ply on those old wheels.