I am running 35s now was running 38's and will soon be running 42's... I will be going 60's w/6.17's in them soon.. my buddy has been running 38's and bigger with 4.10's for a while now with no problems because he was tired of breaking 5.29 pinion gears compare a set of 4.10's next to a set of even 5.29's side by side and you will see what I am talking about ... on the other note keep in mind man axle weight is good for rock crawling as is being wide thats why I like the 60's