I thought I better mention this... I noticed I had begun losing air in my Mudlite XTRs , esp the rear. I have quite a bit of slime in them butair is coming out and it's not around the valve stems either. I have a few cracks running with the tread and had considered just putting in tubes until today.. There it was... the evil: ever so slight....bulge ..Yes, it is there.Between the tread. separation in the making..I still have a lot of tread even though I havearound 600 hrs on this set of tires.I plan to use them as long as is safe then I may get some of those rough riding Essex surefoots. I will probably just replace the 2 rear troublemakers. I do ask a lot of them hauling minerals, posts, pulling heavy troughs etc...I wanted to keep all informed on this tire issue..2200 RTV hrs and counting.. Bordercollie</p>