Which causes more strain on the drive train and axle components? If I’m on an obstacle that I can’t get up at 10 psi locked, should I air down to 6psi to get more traction or bump it? Which is easier on the drivetrain and axle components?
Airing down vs bumping
- Thread starter JMT
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The question is more complicated and more interesting than that. You are getting into the aired down tire territory where at some point the tire contact patch starts to cup in the center resulting in less contact than a slightly higher psi. Less contact and less sidewall support makes things squirrelly and unpredictable.
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Yep, too low can actually hurt you. I've been there and done that.
A lot of unkowns on the bump too, are we talking a Basket/Nashville send it bump?
Right air pressure and crawling should be less problematic than a bump
We’ve worked out that a 17” provides more stability than a 15”, so what is the ideal psi for traction? In other words, at what psi does cupping start occurring so there is no more traction to gain? And when we get to that point does squirreliness outweigh the traction gained?
Also, does terrain matter? I’d think you could air down more on dirt and snow before it became a losing venture due to the malleability of the surface.
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Depends on the tire, wheel, vehicle weight, etc. Though, I believe it to be somewhere around 8psi within a narrow range. This means that when you find it, it would be wise to recheck the tire psi throughout the day to adjust for ambient temps and tire temps.
I’m always reticent to full send. I don’t want to lose traction and then suddenly get traction and snap a shaft. So I do a little bump, then a little more, and so on. I’m thinking, do I need to take the time to air down more to avoid so much bumping?
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Like JJ said, takes some trial and error to find the right PSI, the PSI on my TSL SX is much lower than that when I was running STT Pro, etc... you have to experiment and be willing to make changes during the day to see.
As far as bumping goes, it really depends on the situation. If it is dry rock with traction it is always best to try and crawl, but sometimes you have 3 or all 4 tires trying to climb at the same time and just a little bump (or a roll into and through, not a real bump) will give you enough momentum to get up and over. Sometimes you have just the very bottom of your diff catching and there is no way to work it over one way or the other and a little bump is just enough to get the diff to slide over. If you are in mud or on rock with no traction, then bumping up and over things is the only way and you have to learn when and how much based on trial and error. Crawl when possible and bump when needed, there is nothing set in stone.
As far as bumping goes, it really depends on the situation. If it is dry rock with traction it is always best to try and crawl, but sometimes you have 3 or all 4 tires trying to climb at the same time and just a little bump (or a roll into and through, not a real bump) will give you enough momentum to get up and over. Sometimes you have just the very bottom of your diff catching and there is no way to work it over one way or the other and a little bump is just enough to get the diff to slide over. If you are in mud or on rock with no traction, then bumping up and over things is the only way and you have to learn when and how much based on trial and error. Crawl when possible and bump when needed, there is nothing set in stone.
Ive gone as low as 6 psi and noticed a bit more slipping. 8psi seems to work well with my 15s and 35" MTRs
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Before I had beadlocks, I would air down to 15 PSI and could tell the tire was begging to be lower PSI. Black Friday will be my first run with beadlocks so it will be trial and error for me. I'm going to start at 8 PSI and work down from there.
Bumping can lead to more than just bumping. Most I've seen just try to bump wind up going full send when they bounce because their foot went to the floor. Crawling over is much more effective. It may take several tries to find your line. Start with the line the guy in front of you took, then change from there. No 2 Jeeps are the same and not just because of the driver.
Bumping can lead to more than just bumping. Most I've seen just try to bump wind up going full send when they bounce because their foot went to the floor. Crawling over is much more effective. It may take several tries to find your line. Start with the line the guy in front of you took, then change from there. No 2 Jeeps are the same and not just because of the driver.
FWiW, I have been airing down to 8psi on non-beadlock wheels for many years. The only time I lost beads were on high traction surfaces while turning with the rear axle locked.
I think it depends on the wheels and the tires. I popped a bead on my old wheels at 10 PSI.
Under what circumstances? And even then, so what? Reseating a tire is generally not a big deal.
My original question wasn’t “how” to wheel (I.e. when to bump, what psi to air down to, how much to bump, etc…all things you figure out with your particular setup), but which inflicts greater forces on the driveline and axle components. Obviously there are many elements involved when wheelin, but I’m not referring to things like full send, but responsible wheeling.
Part of me wants to say that getting beadlocks and airing down sub 10psi will give greater traction and allow me to crawl over obstacles easier so I don’t have to bump and endanger components. Another part of me is sayin, “but the increased traction will increase the forces on my driveline and axle components,” so which inflicts greater forces? Bumping responsibly or airing down more? Or is it a wash and don’t worry about it?
Part of me wants to say that getting beadlocks and airing down sub 10psi will give greater traction and allow me to crawl over obstacles easier so I don’t have to bump and endanger components. Another part of me is sayin, “but the increased traction will increase the forces on my driveline and axle components,” so which inflicts greater forces? Bumping responsibly or airing down more? Or is it a wash and don’t worry about it?
The more control and stability you can build into the rig, the better you can utilize the available traction and momentum. A simple change to 17" wheels will accomplish some of this due to the improved stability of the tire allowing you to take more advantage of the optimal tire pressure.
Then factor in multiple aspects like sway bars, shocks, steering, transmission, etc and you get a compounding effect in the amount of control you have as the various systems start working together in more predictable ways.
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