air pressure

[windwalker]

I have a trailer with 12-4.80 tires, and I don't have any idea how much air pressure is correct. The tires are rated around 65 LBs. I believe 65 is to much air. My boat is 1648 with a 50 Merc, loaded with batteries, gas tank trolling motor and wooden floor plus gear. Thanks

 

[rickybobbybend]

A lot depends on the weight of the load and the specific tires. Sidewalls have the max specs. I have the same size tires and my total load incl. trailer is 600 lbs. It tows great at 50 psi, but gets bouncy if higher than 55 psi. You will have a heavier load. I suggest starting 5 psi below max rated and adjust up or down as necessary. Too little pressure, though, and the tires will run too hot.

 

[krawler]

With trailer tires you should run them at max pressure.

 

[JMichael]

Trailers don't have shock absorbers to go with their springs (at least none of mine do). For that reason, I like for my tires and springs to each absorb some of the impact when I hit a bump. So I only air my tires up until the sidewall isn't sagging/bulging outward and the tread has equal pressure across the width of the tire. Too much air and the the tire will bulge in the center and wear the middle of the tire faster. Too little air and the sides of the tread wear quicker like a car with alignment problems. One of the main reasons for developing inflatable tires was for better grip and a smoother ride. If your tire is rock hard with pressure you defeat both of those.

I should also note that I'm running radial tires and not the typical jon trailer tires.

 

[muskiemike12]

I usually have my trailer tires 10 psi below the max.

 

[bassboy1]

On a trailer tire of that type, the maximum load rating is achieved only at the maximum rated pressure....

 

[JMichael]

You might find this useful.
https://www.boatus.com/trailerclub/magazine/2012/june/tires.asp

 

[rickybobbybend]

You might find this useful.
https://www.boatus.com/trailerclub/magazine/2012/june/tires.asp

Great article, lots of good info. Thanks for posting.

 

[windwalker]

Thank you all. JMichael, Thanks for the link. Great info. windwalker

 

[Stefan]

I struggled with this issue on my trailer tires for a while, they are also 4.80/12 size. Load Range C.

I did extensive research and concluded that I am supposed to inflate the tire to the Max PSI Rating. On my tire it is rated for 90 psi... This seemed way too high so I researched more and more. The 90 PSI rating checks out as correct. Trailer tires have a much tougher sidewall than radials, so they can be inflated more... It's why they dont have similar ratings to our radials on cars or trucks which usually are about 30 PSI..

To sum up, inflate the tire to the MAX psi indicated on sidewall, even if it seems high compared to your vehicle.