Airing down 275R55x20 (33") tires

[ItsmeMrWright]

Hey y'all.

I have been watching a lot of videos by various YouTubers running around trails in my So Cal desert and mountain areas and they all mention the need to air down for rock crawling. Understood. My concern with the relatively low sidewall profile of my General A/T tires is the possibly of breaking a bead if a sudden rock finds it's way.

I have them at the factory settings of 33PSI, and wonder how low would be safe to avoid any bead break and providing some assitance with ride quality. Anyone have any relevant experience?

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[Neomonk21]

When I air down I am usually pretty conservative so I go down to 20-25 PSI. I usually run my tires around 38 PSI normally. I don't usually go any lower because where I go off-roading I don't really need it and I also don't like to wait that long to air them back up at the end of the day. I have never had an issue with them coming off the bead. You could probably go down to 15 PSI and not have a problem but that's just my wild guess.

EDIT: I agree with the other replies. My reply was based on the stock 17" wheels.

 

[azmojave]

I wouldn’t go below 20 with that slim sidewall but you might get away with more. If you plan to do more off-roading you might want to consider 17’s.

 

[JTdiRtyD]

Can you air down a 55 sidewall (20 inch wheels from your other posts), sure, but it's probably going to be minimal improvement TBH. If you're looking at off road and crawling, I'd look into a 17inch wheel as @azmojave suggested. You're going to get more sidewall to protect your wheels from impacts, and you're going to get more squish when airing down to not only better traction but also significantly improve ride when off road.

If you don't plan to off road often, you can air down those 55's and probably get away with it, but if you plan to off road often they are not an ideal size.

 

[Sandman 4x4]

Hey y'all.

I have been watching a lot of videos by various YouTubers running around trails in my So Cal desert and mountain areas and they all mention the need to air down for rock crawling. Understood. My concern with the relatively low sidewall profile of my General A/T tires is the possibly of breaking a bead if a sudden rock finds it's way.

I have them at the factory settings of 33PSI, and wonder how low would be safe to avoid any bead break and providing some assitance with ride quality. Anyone have any relevant experience?

You won’t get much advantage with low profile tires at all compared with high profile tires. Like 255/80-17 also at 33.1” tall. But yes you will risk breaking the bead!

 

[Bandit’s Lair]

I had a reply all typed out and then saw the 20”. For wheeling down here in SoCal you really don’t want a 20” wheel unless you’re up on 40” tires. I’ve never broken a bead but I’ve burped a bead plenty of times. Those wheels will get eaten alive. Just pick up a set of 17” for wheeling.

 

[wuykats]

The MOAB wheels on the stock TJR's were well known for their ability to hold a bead at low pressure, I ran as low as 10 psi, but usually were at 14 psi or so. Now, with our JKUR on 17's and 35's I usually run around 16 to 17 off-road. Same with our JTR on 17's. With 20" wheels you won't gain much sidewall flex since there is very little sidewall. If you plan on wheeling your truck very much at all, as others have suggested, go to higher profile tires and smaller diameter wheels.

 

[Janster]

We used to air down to 15psi on 35x12.50’s on 15x8” wheels.

If you’re new to offroading……you should start on beginner / easier trails that probably don’t need you to air down at all. I mean…. You could air down slightly and not even have much or any benefit by it. So….. that depends on you…

With your low profile tires….experiment with it. Drop 5psi and see what it feels like. Then…drop down another 5psi. You might not notice any difference. Think about your drive home…. are you gonna be able to stop somewhere to air back up?

 

[ItsmeMrWright]

We used to air down to 15psi on 35x12.50’s on 15x8” wheels.

If you’re new to offroading……you should start on beginner / easier trails that probably don’t need you to air down at all. I mean…. You could air down slightly and not even have much or any benefit by it. So….. that depends on you…

With your low profile tires….experiment with it. Drop 5psi and see what it feels like. Then…drop down another 5psi. You might not notice any difference. Think about your drive home…. are you gonna be able to stop somewhere to air back up?

Thank you. Not new to off roading, new to Jeeping, but never had LP tires for off road before. I do have a plethora of emergency/recovery gear including an airmoto and extra battery back up for refill. I tend to avoid the really rocky overland trails since my wife is disabled and I have to take a lot of precautions for safety.

 

[Janster]

Thank you. Not new to off roading, new to Jeeping, but never had LP tires for off road before. I do have a plethora of emergency/recovery gear including an airmoto and extra battery back up for refill. I tend to avoid the really rocky overland trails since my wife is disabled and I have to take a lot of precautions for safety.

When you go exploring, and you’re being cautious with your wife on board....I’d highly recommend having a friend (in another capable vehicle) with you.

I’m sure you know this already…
Make sure your spare tire & jack are usable in offroad terrain. Sometimes, those factory jacks just aren’t good enough (or un-usable) in ‘uneven’ or soft terrain. A lot of folks who offroad regularly, have a hi-lift jack with accessories for various jacking purposes. That same hi-lift jack can be used as a WINCH in a pinch (when equipped with Straps, d-rings, etc). Putting the spare inside the bed will make it easier to access it (Versus being underneath).

 

[Zachanadandy]

I disagree completely with the don't air down advice. With limited sidewall I'd argue you need it even more. The potential for wheel scrapping is real, but in the rocks that happens even with 39s on 17" wheels. At a given psi they will ride stiffer and conform to the terrain even less because of the lower profile making airing down even more necessary. 15 psi is more than enough to keep the tire on the bead and will ride much better and provide better traction. Will it be as good as the same tire on a 17" wheel? Obviously not. Will it be easy better than a low profile tire AND street pressure? 100%.

 

[JTdiRtyD]

I disagree completely with the don't air down advice. With limited sidewall I'd argue you need it even more. The potential for wheel scrapping is real, but in the rocks that happens even with 39s on 17" wheels. At a given psi they will ride stiffer and conform to the terrain even less because of the lower profile making airing down even more necessary. 15 psi is more than enough to keep the tire on the bead and will ride much better and provide better traction. Will it be as good as the same tire on a 17" wheel? Obviously not. Will it be easy better than a low profile tire AND street pressure? 100%.

Yeah, I don't disagree that you can't air down a lower profile tire, it's just not going to perform as well due to a stiffer sidewall. 55 series sidewall isn't that low profile honestly, so it should squish some.

Back in my young and dumb days I ran a, IIRC, 40 series down to damn near nothing. Sidewalls were stiff enough that visually it didn't look low, but I could feel one corner was squishy with bumps and corners. I ended up driving 30 miles home from work before checking it and found almost no air in it. Granted that was a much lighter vehicle, but shows just how stiff those sidewalls can be.

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