I run 31"x10.5" all terrains at 15 psi
Mud terrains require even less air pressure due to the stiffer sidewalls

 

Pump works great on the 31x10.5R15s on my XJ. 15 PSI to 28 or whatever I actually run on the highway in just a few minutes.

On the truck it's a different story lol. 265/75R15 on a 3/4 ton GMC, 20 PSI to 55 PSI takes a fair amount of time!

 

I'm on 31s now, duratracs like 15psi with the 2-ply sidewalls, wondering how long it'll take to pump them up to 33 and how much difference 33x10.50 will make in pump time.

 

That wil depend on the CFM rating, cubic feet per minute. At both zero psi and at 30psi. Many pumps show both ratings.
The MV-50 is a good pump for tires. I use a VIAR 400, and a split air hose that fills two tires at once, just saves the trouble of having to air up four tires individually.

 

The 12:50's should work well for you. I had that size on my 88 k1500. It is a single cab and do to the heavy weight up front they helped, but not much. Even when going down to 15psi it would over heat over a short distance. Weight distribution is very important. I had 11:50's on my 84 CJ-7. At 15 psi it would easily roll in the deepest driest sand we had. I also had a 4 core radiator and that really made the difference. I could drive around all day in second gear and the temperature stayed cool.
I have the 2000 WJ now. I have no idea what size tires are on it. Some street tires I bought it with. Living in California doesn't offer the day to day opportunity we had on Kauai to drive on the sand. I have no idea what this vehicle is capable of. I haven't had it long and its had a charmed life of freeway driving and trips to the grocery store so far. I brought the Chevy truck here and it has 11:50's now. The 12:50's were shot and needed replacing. I put the smaller width on since we'd be living in asphalt land for the next 2 years at least.

 

Hell I never though of the split air hose idea I have a Viair also and when in town the next time will get the parts to do this.


Thanks for the idea!

 

im Assuming your referring to brigantine? I have only had the jeep there a few times. I have 35in km2 have 14lbs in them and I drive most of it in 2 wheel drive. Now that I have kids I take my yukon on nitto terra grapplers aired at 35 and it does great.