Tire Info

Robert812 wrote:
Hi everyone and thank you for your help. My KZ is a 1997 Sportsman weighting at 5600 dry. (wow) anyway I called Big-o and found some tires. Commodore Radial ST st205/75R15C Ordered 5 tires. Now I know I'll be safe on the road. Again thanks for all your help. Hope to see everyone camping. Be safe

load range D or E would be better. And have them put in metal valve stems.

Hi everyone and thank you for your help. My KZ is a 1997 Sportsman weighting at 5600 dry. (wow) anyway I called Big-o and found some tires. Commodore Radial ST st205/75R15C Ordered 5 tires. Now I know I'll be safe on the road. Again thanks for all your help. Hope to see everyone camping. Be safe

Bias ply tires tend to be cheaper in price, and are slightly better for off road or rough road towing. Radial offer better gas mileage, better for long highway towing, and last longer. Most mfrs now offer radials as standard.

CapriRacer make a good point on number of actual plies in a tires carcass. Even my load range E tire 10 ply rated have a 2 ply sidewall however the two plies are much heavier than a lower rated D or C or P tire.

Looking at the new 25' KZ Sportman trailer shows a 4800 GVWR which has a 1200 lb per tire as a minimum load requirement. Your P205/75-15 may have 1453 lbs capacity at 35 psi.
Years back we used 32 psi rated P tires on tandem axle trailers but at only 32 psi we also broke the beads loose when side scrubbing around corners (the tire bead comes unseated with sudden loss of pressure). If you stick with P tires look for one that carries 44 + psi. The higher pressures insure the tires beads stay seated. The beauty of P tires is their not speed restricted to 65 mph as the ST tire nor do they have ST tire reliability issues.

If your needing more sidewall strength the ST205/75-15 C load range is rated as a 6 ply at 50 psi at 1820 lbs capacity which should be within the wheels pressure and load capacities. I would stick with a radial on a highway trailer. Right now the ST8008 Maxxis has a better reliability record that all the other ST tire brands.

And just an FYI:

Radial tires are generally built with 2 radial plies (bead to bead which includes the sidewalls) and 2 additional steel plies under the tread. Sometimes there are nylon (or generic name polyamide) cap plies ( 1 or 2).

This is true for passenger car tires, light truck tires and ST tires.

Variations: Small Passenger car tires may need only a single ply for strength purposes.

Large truck tires (over the road size) are frequently made with a single steel body ply. These tires usually have additional plies in the belt area that function like cap plies.

Some off road LT tires may use 3 sidewall (body) plies. This is more for damage resistance than strength.

US regulations require the construction to be written on the sidewall of all street tires. It will appear in the form:

Sidewall: 2 plies polyester
Tread: 2 plies polyester, 2 plies steel, 1 ply nylon.

(or what ever the construction is)

Likely came with ST205/75R15's? There should be a label near the tongue which gives TT GVWR, AND tire size. You might look for it.

They don't MAKE a 7 ply ST radial tire but you can get a 6 ply RATED (they're radials so really don't HAVE plys) which is a load range C tire. I would ONLY recommend this if you buy a Maxxis tire. Nearly all others are "born to blow up" For what it's worth, if you've been running a passenger tire on a duel axle trailer you've ALREADY used up most of the luck you have coming :)
Good luck / Skip

You have passenger car tires on your trailer. OUCH!
Replace them ASAP with a quality ST radial tire. Do not use bias tires.
The most popular ST tire is made by Maxxis. There are other ST tires that might be worth checking out. Hercules, newer Carlisle RH, and Tow Max. All of these are ST tires that come in your size.
Be sure to have them balanced, too.

The plies reinforce the tire. Hence, the more plies, the more reinforcement. 2 ply tires would be more prone to punctures and failure. Obviously, the greater the reinforcement the harsher the ride. Bias ply tires have the plies at a 60 degree angle to the direction of travel while radial ply tires orientate that to 90 degrees. I would not run the 2 ply tires. They were put on your trailer to minimize the weight.....Dennis