after what size tire should i plan on getting bigger axles?

 

Why would you need a bigger axle for tires? You may want to change the gears, but I know someone who has 38's on a Dana 35 with better gears and does fine.

 

this is true, but you definitely need to gusset the axle if your going over 35's and wheeling it hard. Ive seen a few D35/30 combo not stand up in strenuous situations. I would recommend going with D44's or gusseting your axles if your going over 35's.

or wheel carefully

 

I personally would move to a d44 after a 33" tire, an 8.25 for under 33".... but some of us are a little harder on axles than others. I have seen a bunch of mall crawlers that run 33+ on d35s and 8.25s with no problems.

 

even if you truss a turdy-five, when you break a shaft or c-clip, your still losing your wheel.

33s on a d35 max. upgrade to at least a 44 for up to 36s. then a 60 or 9" for anything bigger. but you better upgrade the front accordingly.

 

x2

 

I have seen a locked D35 break a shaft with 31" tires and hold up to 38s all day long with a limited slip. I think the answer is in the abuse.
Andy-Ironman4x4