42 front and 45 rear. Very nice even wear after 8k miles

 

As far as the 35s go when I used to work at dicount tire a yota came in riding on 44s! YES 44s! we rotated the tires and my eyes almost popped out when I saw the pressure was at 12psi all around. the customer wanted them that way and our manager pointed out the larger the tire the less air pressure. Such as Bigfoot runs 3psi and a 21speed racing street bike has about 110-130psi. sounds strange but oh well. I currently run 245/75 16 Goodyear mtrs off a Jeep Rubicon which are load range E(80psi) and I run them at 45psi on my 86 runner. But when I used to be a Ford man I had a 1979 Bronco on 35s(curb weight 6900#) and I ran 32 front 30 rear with a little buldge. With no slight buldge your tires might be too hard which will wear them out faster, and at the cost of 35s I wouldnt take any chances.

 

It is true, it totally depends on your particular tire. Never exceed tire inflation rating. But, in my experience, I never had any wear problems taking it right up to tire inflation max pressure, in an effort to squeeze the last drop of gas mileage out of my vehicle. Of course, that's just for on-road. Off road, you need to lower it depending on terrain, but that would be a different topic.

You also gotta watch out for brand differences. I once bought some 31's dont remember the brand, that were about an inch lower in profile than General Tire 31's. Both tires were exactly the same according to specs, but in reality one was taller than the other, and quite noticeably taller. Go figure. Max pressure was also different. One tire was allowed up to 44, another up to 35 only. Mix and match, but beware.

On my current tires, I run 35 all around, with no noticeable problems.

 

Why do most people run more pressure in the rear than the front? I always thought you needed more in the front to offset the weight of the engine.

 

Now really.....If you have truely looked at tread wear you don't need as much in the rear.

I have 36 up front and 34 in the rear with even tread wear with the stock Dunlops. I could drop down to 35/33 but am getting good gas milage without a bone jarring ride at 36/34.

 

You do need more in the front. In fact most door jam stickers suggest at least 3 to 15psi more in the front, it just depends if you're in an Echo or a 1 ton truck. My work truck is a hunk-o-*^%$ dodge 3/4 ton and the sticker says 65/80, but thats for haulin weight not just the engine which is typical of most cars and 1/2 ton trucks.

 

for that guy that mentioned Sams club.. yes... we do them at a roundabout number... 32 for cars, 35 for trucks and vans.

unless a big dually comes in or a large chevy or dodge, then we fill them up a little higher, normally 40 in the front and 45 in the rear. duallys get about 60 or 70 in the rear. normally, we'll look at the door jam though if we are unsure

if somebody requests them to be filled to a certian spec, then its all yours.

 

32 psi front and back...i am running Michelin X Radial LT's 265/70/16...make sure you are checking these tires when they are cold folks! I wouldn't go near the max inflation rating...just asking for trouble, especially in the summer when if you do check the cold and the max is 45psi and you have them at 44 psi, when you start driving in 90+ degree weather they will probably go over the max rating. IMHO

 

Addin air to the drive tires will increase gas mileage.

 

45 psi front and back during the summer (50psi max rating)
32 psi front and back during the snowy season (for xtra traction)

The higher pressure does improve gas mileage and won't hurt the tires unless you are on really rough terrain. Mostly, higher pressure just makes the ride a bit bumpier. As mentioned, make sure you don't go over the max psi in hot weather. Also keep an eye on center tread wear.

 

Agreed, all measurements should be taken when the tires are "cold", ie not having been driven. If they are at rated max when cold, there is nothing wrong with them heating to over max during normal use. That is perfectly normal and has been factored in to the max psi rating.

Running near max psi is perfectly ok, provided you are not overloaded, have poorly maintained, overly worn, or old tires. (then it IS an issue) 18 wheelers have their 14plys typically at max psi (~110 psi if memory serves me) for their entire lives, the same is true of most 3500 duallies.

 

and wait for there to be a loud noise!



About 32-36 psi checked while hot is what I always run on the road.



Brian

 

btw - if you are bored and want to use some math (always a GREAT hobby) you can calculate how much your tires inflate when hot, using the IDEAL gas Law. PV=nRT

P = pressure (kPa or atm)
V = volume (L)
n = Number of moles
R = Ideal gas constant
T = temperature in Kelvin (K = C + 273)




hmmm maybe I shouldn't have had that last beer....

 

wholey sheepdip! WHAT DOES IT ALL MEAN, MAN!

~
a

 

I usually inflate mine 5 psi less than the max rating on the tire for daily driving on pavement.

Chris

 

Fourty-some PSI??? Help this fella out, guys! 35 Max w/street rubber, and that's probably a wee bit high.

 

Hey guys, I'll reprint this article again for this thread. Remember, proper tire pressure has to do with load and use at the particular time. Hope this helps
Mick

Letting the Hot Air Out of Tire Talk

Tire Pressures for 4-Wheeling

by Harry Lewellyn

Experiences Playing in the Sand

I guess I should cut those reluctant to lower their tires down to sand pressure a little slack. My first time onto the beach in San Felipe, Baja, I did the air pressure trick, with a little unwillingness, and wasn’t sure it was really necessary. Then, over the next three or four years, I would first tackle the mellow white stuff at full street pressure and when all my power, skill and finesse failed, I would let ‘em down and move ‘em out. Me, low range and low gear, would struggle along at a whole five MPH. Deflation they defied resistance as I sailed along in high range, OD, at whatever speed I chose! Time and again, year after year, I tested the softies with the same undeniable results. Low tire pressure just plain works in the sand!

What Affects Optimum Sand Tire Pressure

Optimum sand tire pressure is a combination of many things, of which old husband's tales are least productive. However, your tires, their construction methods and materials, what your car weighs, how it is loaded, and wheel width all play into the sand-pressure tire formula with predictable results. For this article, I will neglect tire temperature which I suppose could be critical if you test below freezing and play at +80°. Why low pressure works and how to determine your best sand pressure follows.

Why Low Pressure Works

It’s a simple fact, which some diehards still deny, the bigger the footprint, the softer the stuff you can travel. Mother Nature knows it. Take a look at the feet of camels, polar bears and marsh birds. They are big and spread out to distribute their weight over a larger surface area. For those who say skinny, hard tires are better for snow, mud or whatever, please tell me why they don’t use ten-speed bicycle-type tires on snowmobiles? Sand rail people and mud boggers know big feet work better too! With that out of the way, lets take a look at tire pressure and footprints.

Tire Pressure and Footprints

Right next to your wheel, on the tire, find the small black print that specifies maximum load pressure. For example, my BFGoodrich Radial All-Terrain T/A 30x9.50R15LTs state 1990 pounds at 50 pounds per square inch (PSI) cold. Most folks, generally including those who install tires, run them up close to this, and neglect the actual term, "MAX. LOAD" pressure. The street pressure, TREAD FOOTPRINT figure below represents Coyote assessed over inflation.

 

I just thought I would throw in my situation and see what everyone thought. On my D load rated Revos the max tire pressure cold is 60 psi!!! I usually run them at about 38 to 40 psi but they always look a little flat. Should I put more pressure in there? Its not like I'm carrying all this stuff around either, this is with an empty runner.

thanks

 

This is very true. When I had 38's on my old truck I would run 18-20PSI and my buddy with 44's would run about 13-15. It is pretty crazy but thats how it works.

 

Hey guys, sorry I didn't have the complete article in my post above.

Here is the complete post and tells us a lot about tires.

Mick