On my Lazer's rear tires (Carlisle 2ply Turfmasters 24-12x12's) I have two sidewall bubbles/bulges! Wasn't like this at the start of the season. I washed it thouroughly 2 weeks ago and literally scrubbed the tires and wheels. Made it look like a new mower. Tires were fine then. Anyway, do you think that this will cause a problem? I can push on the bubbles and they don't seem to have the same psi of air as the tire does. They seem real light and easy to push compared to the rest of the sidewall. I just dont want them to pop that one ply that the bubbles are in and cause an unfixable leak The sidewalls look wrinkled like a drag slick where these bubbles are. Also on another similarly related note....Do you guys with these tires notice that the tread that contacts the ground is concave? What I am saying is the tread on the tire is only worn on the outsides, the inside tread still has tits on it and isn't worn at all. This is due to the tire dipping in or concave. If I put 10psi on all 4 tires, it is really noticable, I put 15 in and it improves it slightly (squares up the tread more even all the way across). When they were new, I could put a ruler across the tread and stick a pencil under the ruler in the center, while the ruler rested on the outside tread! On these tires they say "MAX INFLATION 10 psi" Why does Exmark suggest 13psi ? Is there any type of tire warranty for this type of thing? I'm just worried that when I go to replace that one defective tire, that I will have to now do both (due to 500+hrs wear) or the mower will sit crooked. I understand that Exmark "matches" tire circumference and keeps them similar. Where do they measure? I would have two very different measurements if I measured the center vs. the edges with these tires! Thanks in advance!