Picking a nit since all your info is well thought out and accurate.

It's bias ply or radial tires.

 

depends on what your trailer requires. some 5th wheels require radial tires. what sucks about those is when they blow out. shrapnel and cap. ouch. my car hauler calls for bias ply, when they blow out, they just blow out the center and crush inward with the sidewall saving the wheel because i run 10 ply. stiffer walls. my truck calls for 10 ply radial for the weight of pulling/hauling. i prefer a tandem vs. a single axle on a trailer. if one tire blows, i got at least one more on that side that'll support the load until i can get it shutdown. to each his own.sorry, i run the pressure the tire requires, nothing more, nothing less. no problems. it'll expand/retract on its own.

 

Lots of useful info guys. I checked tires today. There is no mark on the tire saying max psi. Only: Made in Taiwan, Electra and 5.30 x 12. Nothing else. Since I discovered a lot of cracks on the sidewall, I want new ones.
It's 4 bolts on 4" design. I would like to use 13" tires. There is no big difference price wise. Buying tire-wheel package. Hoping that works fine.

 

jaybeecon55

Hey thanks for the spell check.......HA! don't know where that b-y-a-s-s came from???
I knew better, get in a hurry to type I guess.......

Sotto66....13" will be fine if you have enough clearence above the tire and on the inside.
The 12" still should of had atleast a ply rating some where on the tire sidewall.
4ply = 35lbs
6ply = 50lbs.
8ply = 65lbs
10ply = 80lbs

 

Bringing this thread back; on my 4x7 the tires say max is 90lbs, but I don't know if I need that much. I usually run them at 50, but yesterday I looked at the tires and noticed the left tire has more center wear than the other does. I always check to make sure both are aired equal before going anywhere so I don't know why one would be more worn. Next time I take my ATV anywhere on it should I just pump them up to say 80lbs?

 

I had one tire on a 5th wheel that had noticeably more of a crowned look across the tire than the others, even though the pressures were the same. Tire guy said I was ok, but the next trip the tire flew apart, leaving only the sidewalls on the rim. Luckily I got it stopped safely, and it didn't do much damage to the trailer.

Anyway, I think the tread looked more rounded was because of belting being broken or delaminated.

Pressure wise, you might look up what the tire maker says, but if in doubt I'd run them at rated pressure. For me anyway, I don't get to use my trailers enough to wear the tires out before they should be replaced due to age, and I'm more concerned with a tire overheating and/or sudden failure than I am with maximum tread life.

 

Thanks. Next time I load it maybe I'll do 85 that way it has room to expand after it runs to get close to the 90. Sure seems a lot for those smaller tires. I'll have to go to tire store because I don't have a compressor and those at gas station don't seem to have enough to fill them more than 53.

 

Center wear means you have too much pressure, while equal shoulder wear on both sides of same tire means you have too low pressure.

One shoulder wear usually means either toe-in or toe-out depending is the wear inside or outside and some cases curb side tire has uneven wear caused by the road cross-section shape, at least that's what happens on 18-wheelers and those trailers.

On my single axle with 15" tires, I change the tire pressure to match the load as without the load and full tire pressure it will bounce all over. While we tow 1100 miles from KS to UT with one atv, riding gear and rest of the crap, I usually have the tires with 35-45 psi. When running with light load I reduce the pressure to 15-20 psi and the lower tire pressure will work as suspension absorbing the road bumps.

 

Wow 90psi is a lot...most load range E tires take 65 to 80psi. I've got some Interco radial trailer tires that have been great...load range D max 65psi. I usually run 50 to 55psi and they have been wearing great. This is on a single axle 5'x14' trailer.

 

Some of the smaller trailer tires are designed to run pretty high pressures.

I assume it has to do with how they are constructed, and the mass available to dissipate heat.