A Heep owner buddy of mine and I had a discussion about tires recently. Since my A/T's will last another 20K, M/T's will have to wait. He said he's seen people air down A/T's to 15-20 psi and they grip really well. I need the additional traction, but am really afraid to air down an A/T that low. BTW, I have 265/75 Eldorado ZTR's ~ Cooper ATR's. Any thoughts?

 

I dropped my 33x10.50 ATs as low as 7 psi:





Find out how low you can go by determining your "sand pressure":
- http://4x4now.com/sfjun96.htm

 

On road keep them at 32 to 35psi, offroad depends on surface. Sand and snow I have heard down to 7psi like 4crawler to 15 for rocks and dirt.

 

i have cooper st-c 10 ply and i drop them to 7psi, i had p-rate 4 ply s/t's and had them to 10psi

 

It takes some experimenting and differs with the conditions. When I first got started, I gradually took the tire pressures down each trip. In the Ohio mud, I would see a HUGE traction increase at 15 psi. Out here in Colorado now, I don't need to go that low - 19-20psi seems to work well and takes a lot of stress off the sidewall and saves some ground clearance. In Moab, I think I could almost get away with not airing down at all.

One of the local 4WD shops in Cleveland had a little test track behind the shop, and you could go out there and play with tire pressures to see what worked, and if you popped a bead, just take it in the shop and reset it.

 

Airing down your tires is a easy way to gain traction. A bigger footprint is better in sand/mud, but in snow the tall skinny tires IMO are better. It all depends on where your at. Just remember to air up before getting back on the road. I've ran my old 31" BFG AT down to less than 10 psi in sand. Not having hundreds of horsepower, I'm not worried about slipping a bead!

 

I run my 33x12.50's at 12lbs. Never had any problems.

 

on my 33's i ran 5-10 psi crawling, on road i ran them at 22-28 psi depending on what time of year it is, only just to keep a good even wear all away across the footprint. plus i never have to far to drive around here so i dont really have to worry about psi vs mpg.

 

I live and wheel in the mountains of the northwest and run into a ton of snow. there are two schools of thought. the first is bigbluepile's philosophy of tall skinny tires at road or close to road pressure. this allows heavy vehicles to cut through snow. this is the philosophy of the military in most cases (besides super deep snow). what we usually run are wider tires at lower pressure. the bigger foot print does the same thing it does on sand...allows you to ride on top of the snow. it is a very surreal feeling to park you yota for lunch, jump out of the rig and end up waste deep in snow while your yota is sitting very high in the snow. its all about your foot print and pounds per sqauare inch. wheel safe.

 

why NOT air down?

I aired my all-seasons down to ~20 psi on my subaru (didn't want to go much lower....they had pretty thin sidewalls...).

and my liberator A/Ts, I'd frequently take down to 12-15 psi.

 

I used to run my wrangler GSAs at 4 psi

never lost a bead

 

Whats the difference in airing down a A/T vs M/T... I have gone as low at 10 on my A/T's, and 6-7 on my M/T's...just different situations...

go ahead and drop em...

 

since cleghorn, i air down to 15 or 12.

 

Thanks for the input guys! I'll do some experimenting and see how they do!

 

I'm curious about this now too