I put the Scorpion STR on my truck last week and the dealer put 30psi in them. I thought was waaaay top low (max is 80psi). I have about 60 right now. Anybody know what pressure works well? Should i follow manufacture 30psi even though these are 10ply tires?

 

Yes, 30PSI will give the best traction and ride. Now for load capacity it may need to be brought up depending on the weight.

Next, if you plan to have a tire with more than 45PSI you will need either metal valve stems or high pressue stems with metal tubes. When the pressure is greater than 45PSI and a load is applied, a bump in the tire can cause the pressure to really spike causing failure (blow out) of standard rubber valve stems.

The 10 ply will run cooler and give you longer tread life without raising the tire pressure. These 10 ply tires are rated over 3200#/tire at max inflation. If you are running a F150, you won't need but a small part of that load rating.

 

30 is way to low for a LR E tire. I ran my LR E's at 50 on my F150. You might ask your tire dealer why he is putting 30 in that tire when the new regs for tire monitors are required to go off on a max 80psi tire at 35psi.

 

I think I will have to disagree with you on this one. My other vehicle ('03 Jeep Wrangler Rubicon) has factory equipped Goodyear MTR's 245/75R16, load range E, max load 3042 lbs @ max pressure 80 psi. Jeep's recommended pressure for this combo is 33 psi, less than half the max tire pressure, since the four tires carrying capacity is 12168 lbs at max pressure, and the Jeep weighs around 3500 lbs. Many Rubi owners think that 33 might be a little high, and run 30 or so.

Although caballero didn't identify his truck, 4700-5000 lbs empty is probably a decent ballpark guess. There's no way you need 80 psi or even 60 psi. I'll bet a "chalk" or "wet spot" test would indicate substantial over-inflation at those presssures.

 

All good points. I have a set of Scoprion's on my custom wheels for a year now and I run them at about 45-50#. I found the lower pressure was too low and conversly, of course, the crazy 80# max. was way too hard and unnecessary. They have been wearing great. They still don't get as good a traction as my Goodyear eagle F1's, but those were way soft and didn't last long at all, no suprise its always a trade off.

 

As I stated, he should use 50. 30 might be okay in the mud, but on the road it will build a lot of heat. The new regs for tire pressure monitors state that they should be set off when the 65 or 80 psi max tire is at 35. Originally they were talking about 42 to set off the 80 psi tires.

There is a chart most of the way down on this page.

http://www.nhtsa.dot.gov/cars/rules/...nalrule.6.html

Also I ran LR E BFG ATs on an F150 for over 2 years and 40k at 50 psi. Still had tread on when I traded the truck.

 

We may just have to agree to disagree on this one. I still think 50 psi would be too high for an empty or lightly loaded F150. Now in giving my Jeep as an example, I was not suggesting he should go as low as 30 psi. I agree that would be a little low for an F150. 35 to 40 should be plenty, though. On any given vehicle, there is no real reason to change the tire pressure significantly from the manufacturers sticker unless heavily loaded, even if you change a tire size or two or go from P-metric to load range E.

 

I know you are speaking in relation to the Scorpions, but I have TOYO that max out at 65 cold pressure at a load of 2910 lbs and TOYO recommended 45 for the front and 61 for the rear, and their analysis was based on what the factory (load rating)was. I think no one will completely agree with THE BEST psi, but experimenting does not hurt as long as you don't blow it out. For offroad/ crawling I have heard of people going down to 8-15 psi. And some have recommended going higher pressures to get better gas mileage. I keep mine at 50psi all around, although the ride is bumpy. But that's just me. Good luck