I was looking at my BFG tires yesterday and i noticed that they are really low. I put a psi tester to it and they were at 30psi. I read the side wall at it said "do not excede 2550 lbs at 50 psi" does that mean I run them at 50psi while on road? I filled them up to 48 to she what would happen and they look better. Can anyone tell me the correct psi?

Thanks
Chris

Chris, the BFG's under an Explorer really don't need that much pressure. I found about 29 pounds to be good for me, but I have a somewhat different size, being metric 16 inchers and all.

Do a search on the forum for tire inflation and you should see a post about how to find the correct pressure by drawing a chalk line on the tire. This will show the proper pressure at least as far as even tread wear is concerned. You can then adjust higher or lower depending on what you like as far as ride and handling.

The 50 psi stamped on the side of the tire is the pressure you would use when the tire is loaded to its maximum weight rating, in your case, 2550 lbs. Now an Explorer only weighs about 4000 to 4600 lbs, so each tire is only carrying about 1100 lbs, give or take a bit. You don't need that much air pressure in them to deal with that kind of weight.

Keep in mind that the tire should normally flatten out a little at the bottom where it contacts the ground. I would venture to say that your tires with 48 psi in them are nearly perfectly round, and have a very small amount of tread actually putting any weight on the ground. They probably ride pretty rough as well.

We have 32x11.50 on 8" rims on our 92 XLT (4door) and 32 is the minimum pressure we run them at.. on the street.. if we go any lower the locker wiggle and the tire screeching is very anoying.. not to mention gets us pulled over (the screeching)..

We also don't have sway bars so when it got squigly it really got squigly...

If you don't have much of a lift (<4").. lockers.. and have sway bars you can prob run 30psi.. You really need to do the line test.. to see how much of the tire is actually on the ground.. you want it flat.. (or close to).. not bulged in the center.. or the center will wear out..

How do I do the chalk line test? My tires seem to be a bit more rounded, but when they were at 30psi they seemed to buldge at the side wall too much. Is that ok (to buldge on the sidewall)? And yes, when I filled them up to 48 it was so much rougher! It was so rough that it knocked one of the wires off of my fog lights tonigt on the way home from work.

Thanks for the help
Chris

I had that same problem when mine were put on. The guys at the tire shop look at the maximum rating and just assume your tire should be that pressure. At 45psi, mine rode like a damn tank. Over the course of several days, I lowered the pressure each morning ( cold pressure )til I got to where it rode smoother. At 32psi, it seems to drive and ride pretty good. I haven't seen any bad wear marks yet, so I assume they are running straight and flat. Also, the sidewalls are three ply so it makes them very stiff, you don't want them to bulge too much, but not too little either.

Ok, so a little buldge is good. I am going to go air them down a bit now I think. I have to go get one repaired because it has a screw in it and is loosing air. I think I'll air them to like 35 or so. I'd still like to know how to do the chalk test though

Thanks
Chris

35 psi is still too high for those tires but a good place to start the chalk test.

On level pavement with a straight parking lot ahead of you, make a chalk mark sideways across your tread. Drive straight ahead 30 yards or so and check the chalk mark. Since you still have too much air in the tire, you will note that the middle of the chalk mark is gone while the outsides are still chalked, since the outside treads weren't touching.

Air down a couple of psi and repeat until your entire tread touches and the entire chalk mark wears off. Subtract another pound or so to let the whole vehicle's weight wear across the entire thread and there's your perfect psi for that tire and your vehicle. My BFG's are 285/75r16, I have a 4dr, and run 28 psi.

Hope that helped.

[Edited by GJarrett on 09-21-2000 at 01:35 PM]

yeah, that helped a lot. I aired them down to 38 fo not, just to see how it was. Not too bad. I'll get a piece of chalk and do that though.

One other thing while I am thinking about it. I went to get my tire checked out that has the screw in it, and the guy said it would cost my $20 to fix it. Is this resionable? He said it would take like 45 minutes, but I have to make an appointment for Monday at the earliest.

Thanks
Chris

A little high, but the way they fix them now it is the better way. Instead of a plug, they take the tire off the rim, patch it from the inside and re-mount, balance. Call around and ask, it can't hurt.

Oh really? That is sweet. I am going to call around to some places tomorrow. Do you think I could use that fix-a-flat stuff?

Thanks
Chris

Discount tire will fix a tire for free. Even if you didn't buy it there.. It can take over an hour (it is better if you bring the tire in off the vehicle so you can leave it there). They do it for free so you will think of them when the time comes to replace your tires...

I like this philosophy.. That is how I found out about them.. and I will use them any chance I get..

Hmmm.... discount tire? I don't think I have seen them here in VA. I'll look through the yellow pages tomorrow to see though. I do like that concept, I bet it works for the most part too!

Thanks
Chris