Hi: Chris R... I haven't had issues with my 15" tires, but had to have all the valve stems replaced. (weakest link) thing!!! There were millions of bad stems mfg'd in China in 06-07 and they all started cracking from exposure. Close inspection revealed even my never used, covered spare, stem was cracked.
I really think a lot of tire failures were the stems letting the air out at hwy. speed. It cost me $30. to have all 3 replaced...cheap insurance i'd say. Alf
escape artist N.S. of Lake Erie
p.s. I run 15" Goodyear Marathons @ 47psi. cold