Road air pressure

[rollingpinz]

I bought Falkin 255/85r16 mt’s. Haven’t had them off road yet so nothing to report. The sidewall says 80 psi max. So my question is what would be a recommended pressure for road driving? 80 would take a long time to reach after airing down for the trail.

[rmel]

HWY Tire pressure mostly depends upon the Tire size and load the tire is bearing.

There are charts on-line for LT tires vs load to get you in the ballpark. You don't
want to over inflate resulting in a small contact patch and wear in the middle, 80psi
is way too excessive for a 2 1/2 ton 710.

Typically, a 710, ~1,200 lbs/wheel, so your looking at a range between 35psi up to 45psi.
I run ~43psi on 265 Toyo's on my 710K and that took some experimentation.

[ChickenPinz]

I bought Falkin LT255/85r16 mt’s. Haven’t had them off road yet so nothing to report. The sidewall says 80 psi max. So my question is what would be a recommended pressure for road driving? 80 would take a long time to reach after airing down for the trail.

I run Falken Wildpeak M/T 255/85R16 tires at 36PSI and am happy with the road performance. Other than undesirable wear patterns (which you'll get with the Pinz regardless), I think your only real risk with the pressure being too low is excessive heating due to sidewall flexing. I think you could run much lower than my 36PSI with little issue. When considering what pressure to run, consider what tire pressures have been tested by automotive engineers for similar vehicles for reference. This is a focus on heating and weight capacity as dynamic handling characteristics are far more complicated to evaluate.

That max pressure on the sidewall is the pressure required to enable the maximum rated load of the tire across all operating conditions. If you are going to load the axle enough to reach the capacity of two tires, you'll need to inflate the tires to that max pressure. Your Falkens are rated to 3415lb each at 80PSI, so call it 6800lb per axle. Empty, the rear axle has about 2200lb on it, so you'd only need that 80PSI in the tires if you loaded the back of the truck with 4600lb right over the axle. Not likely to occur.

For reference, let's consider an FJ Cruiser, which scales around 4700lb and is about the same weight as a 710K (as measured). Running LT265/70R17 tires (factory size), the doorplate recommends 32PSI.

[Stumbler]

You can guess and try what you think will work. But the easiest way is to contact the regional rep for that tire. He has probably seen almost every use for that tire you can think of. If you tell him what the vehicle is, after a short period of shock, you can tell him the weight, power, surface, etc., and he will know. I went through this sort of mental gymnastics when I first put Goodyear 285/70R17 MTR on my truck. Everyone had an opinion. The regional rep was the only person I found to be reasonably knowledgeable on it because everyone calls them with all their unique problems. In my case, the max is 80 psi, but I run 40 to 45 daily, and air down to 25 when needed.

[Hugues]

You can guess and try what you think will work. But the easiest way is to contact the regional rep for that tire. He has probably seen almost every use for that tire you can think of. If you tell him what the vehicle is, after a short period of shock, you can tell him the weight, power, surface, etc., and he will know. I went through this sort of mental gymnastics when I first put Goodyear 285/70R17 MTR on my truck. Everyone had an opinion. The regional rep was the only person I found to be reasonably knowledgeable on it because everyone calls them with all their unique problems. In my case, the max is 80 psi, but I run 40 to 45 daily, and air down to 25 when needed.

Are these with a tube inside ? if so, no issues to air down ?
I'm looking for new tires and here in Switzerland it seems Pinz were registered only to be used with rims for tubes...

[rmel]

The original Pinz came with Swiss Maloya bias ply tires with an innertube.
The stock wheels are somewhat narrow by today's standards at 6.5" and
they do not have internal bead humps.

That said, most Pinz'y owners I have run into as well as the comments made
on this forum have moved to Radials with no innertube.

I don't recall anyone commenting that the wheel won't hold air or the lack of
bead humps is a major problem if you limit airing down to 20psi or greater.
It's a bit of a risk though w.r.t. breaking a bead on the trail at 20psi, I've seen
a few cases.

Some have switched to Wheels made for the Ford Transit which are also 6.5" but
inc. internal bead humps, but that wheel has it's own nuances.

[Hugues]

thanks guys,
i think i will have to cheat the system a bit and use tubeless rims so i can air down sufficiently.

[Stumbler]

This might answer your question: If you are trying to air down the standard 6" tire, I wouldn't suggest it. I lot of people have found that if you go buy 6" tires to replicate the original Malloya look, you might spend $5k to $6k. If you find a set of wheels that are standard sized (roughly 8" wheels with an almost 7" offset) you may then buy almost any manufacture modern style tire. In my case, I decided to have a custom set of wheels made that cost me as much as an entire set of tires, but now I can use any tire I want. My personal preference was the dimensions of the 285/70R17 because it is 1" narrower than most 33" tires and they ride well as a package with alloy wheels. (Lighter than the factory steel wheel plus Malloya)