air pressure...

[kreiten]

just trying to get an idea of what guys are running for air pressue on gravel roads with heavy washboarding... I run 40 psi on the street want to try to find that sweet spot where I can have maximum tire patch on the road to give me more control over the washboarding but not risk the tire coming off the bead, any input would be great, thanks!!!

 

[gaijin]

First, I have to share my opinion of how to handle washboard roads.

It's all about speed. If you are just negotiating a stretch of washboard road between stints on the highway, and the washboard section has turns and can be run at speeds in excess of 30-35 mph, then I would NOT air down just for the washboard section.

40psi is a good pressure for your tires for onroad use. Your tires are not rated for road use below 35psi.

Often, going faster over washboard roads will yield a much smoother ride. It is a question of finding a balance between the tires/suspension and the frequency of the washboard bumps at different speeds. If the washboard bumps are consistently spaced, as is usually the case, by gradually increasing speed you will eventually find a sweet spot that will result in a relatively smooth ride.

If you feel you must air down for the washboards, then I would go no lower than 20psi and go no faster than 20-25mph. Even at that slow speed, I would slow down for curves and particularly large bumps/holes.

For rock crawling and more serious offroad use, your tires are certainly capable of being aired down to pressures much less than 20psi, but are limited to speeds much less than 20mph as well.

In summary, I would try varying your driving technique (speed) on the washboards before reducing tire pressure.

 

[kreiten]

First, I have to share my opinion of how to handle washboard roads.

It's all about speed. If you are just negotiating a stretch of washboard road between stints on the highway, and the washboard section has turns and can be run at speeds in excess of 30-35 mph, then I would NOT air down just for the washboard section.

40psi is a good pressure for your tires for onroad use. Your tires are not rated for road use below 35psi.

Often, going faster over washboard roads will yield a much smoother ride. It is a question of finding a balance between the tires/suspension and the frequency of the washboard bumps at different speeds. If the washboard bumps are consistently spaced, as is usually the case, by gradually increasing speed you will eventually find a sweet spot that will result in a relatively smooth ride.

If you feel you must air down for the washboards, then I would go no lower than 20psi and go no faster than 20-25mph. Even at that slow speed, I would slow down for curves and particularly large bumps/holes.

For rock crawling and more serious offroad use, your tires are certainly capable of being aired down to pressures much less than 20psi, but are limited to speeds much less than 20mph as well.

In summary, I would try varying your driving technique (speed) on the washboards before reducing tire pressure.

thanks for the feedback, I would say my main concern is steep down hills with an open turn and washboarding etc, the first thing I figured out real fast is the washboard sections can be somewhat like driving on snow when they are bad and in a sharp turn, so I use the gears to control the vehicle speed, only using the brakes if i have too... I guess I'll try going down even lower than the 35psi I went down to yesterday, maybe I'll try 30ish psi... what would you run in sand dunes with my tires? do the ARB onboard compressors work for filling your tires back up? thanks in advance for your feedback!!!

 

[kreiten]

I generally drive between 25 and 40mph depending on conditions etc...

 

[GeologistFelix]

Losing the bead is only ever really a problem when you go below 10 PSI, in my experience.

As well, running 20 PSI at higher speeds (~40 mph) on washboard gravel isn't going to magically cause anything especially bad to happen.

The main things that can go wrong, aired down, is either hitting a rock/pothole/etc. that bottoms the tire out on the wheel and damages the sidewalls, or long-term overheating of the tires caused by excessive flex in the rubber as they roll.

The bottoming-out problem really shouldn't be a big factor if you're going responsible speeds. If it's a road that no sane person would go 40 on, don't air down until it feels smooth and then rocket down it at 40. If you're at 20-25 PSI, you're going to have to hit a HUGE hole/rock for that to happen, anyway.

The overheating I would only worry about if you were going very long distances at high speeds, i.e. highway speeds at 25 PSI. Even then, I've been on wheeling trips where we had a compressor failure and had to drive 10-20 miles on pavement at trail pressures, and there was no discernible heat buildup in the tires by the time we got to the gas station and its compressor.

 

[kreiten]

Losing the bead is only ever really a problem when you go below 10 PSI, in my experience.

As well, running 20 PSI at higher speeds (~40 mph) on washboard gravel isn't going to magically cause anything especially bad to happen.

The main things that can go wrong, aired down, is either hitting a rock/pothole/etc. that bottoms the tire out on the wheel and damages the sidewalls, or long-term overheating of the tires caused by excessive flex in the rubber as they roll.

The bottoming-out problem really shouldn't be a big factor if you're going responsible speeds. If it's a road that no sane person would go 40 on, don't air down until it feels smooth and then rocket down it at 40. If you're at 20-25 PSI, you're going to have to hit a HUGE hole/rock for that to happen, anyway.

The overheating I would only worry about if you were going very long distances at high speeds, i.e. highway speeds at 25 PSI. Even then, I've been on wheeling trips where we had a compressor failure and had to drive 10-20 miles on pavement at trail pressures, and there was no discernible heat buildup in the tires by the time we got to the gas station and its compressor.

thanks for the feedback!!!!!!!!!!!!!!!!!!!!!!!