25 x12x10. 25x8x12

 

It depends on what quad and what tire but I would see how it rides with 5 psi for a utility quad. You can adjust from there.

 

7psi is normal or avg psi on all atv tires. However different riders use different psi. Trail rider and a swamp rider will run a different psi. The 26" gators I ran with no air at all pulled like a beast. New atv tires the shop put 36psi in to seal the bead. Didn't release none afterwards. I was haviny a hard ride but helped in deep water air equals floating. My kenda have 3-4 psi where I have found my best riding. I can drift mud and trail ride and climb with ease.