I have a 1990 Toyota 4x4 4cyl Auto trans ext cab. I'm wanting to know if I can run 31x10.50-15 Mud tires on it. It's a completely stock truck with aftermarket 15" wheels. I'm currently running 235/75/15 Goodyear Wrangler radials

 

I dont know what gears you have but it should be fine. Might just give you a little hit with acceleration and mpg. I have them on mine and dont really notice any difference from the 235s. But i am not expecting this thing to win any races.

 

I was thinking about lifting it and putting 33x12.50 on it but I'm afraid to with the auto trans

 

I am running 31x10.50's on my 89. Its the 3.0 auto, but your 4 cyl should push them just fine. They look mean too!!

 

If you do this without gearing you will hate it, the 31's are ok but when I did mine I lost a lot of power so I re-geared. Might find out what gears you have as the autos were geared differently, I went from a 225 to the 31's so I noticed a huge difference but since you are used to the 235's you might be ok with it.

 

the 22re is a slow motor no matter what size tire you use. slap them on, i would never run anything smaller than a 31 on my yota again. small tires look silly

 

well it depends on how soon you plan on buying 33's and lifting. one more thing to keep in mind is if you run 33s you should looking into some gears to help with the bigger tire size. if it was me its kinda pointless to buy 31's and then turnaround and buy a lift and bigger tires.