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One of the most important components of a trailer is the rubber that meets the road.  Whether you pull a utility trailer, car hauler, camper trailer, or horse trailer, having the right tires is crucial for a safe and smooth ride.

When choosing trailer tires you’ll need to take into consideration the size and type of the trailer you have as well as the weight of the load you carry.  To help in selecting the best tires for your trailer, we’ll explain what an ST tire is, how to find your tire size, and go over the difference between Radial and Bias Ply tires in this blog.

ST Tires

Specialty Tires or ST tires are built especially for trailers with a stiffer sidewall to carry heavy loads.  There are two types of ST tires – radial and bias ply tires.

Radial tires are made with inner steel belts running at a 90-degree angle from the tread.  Overall, they tend to last longer than bias ply tires and because of their low rolling resistance, they dissipate heat more efficiently for a smoother ride and better fuel economy. Another key feature of radial tires is they don’t tend to get flat spots on the tires when parked for an extended length of time.

Bias ply tires are built with inner steel belts or (plies) running at a 30-45 degree angle from the tread.  Bias ply tires typically have a stiffer sidewall than radial tires which helps increase stability and decrease sway when your trailer is loaded.  They are also generally cheaper compared to radial tires.

Speed Ratings

All tires come with a maximum tire speed rating, while it’s not usually a big deal for car and light truck tires because the speed rating is usually well above the speed limit. Trailer tires, on the other hand, have a much lower speed rating.  The common speed rating for trailer tires is 65 to 75 mph.  If you exceed the speed rating, the tires heat up causing tire failure and blowouts.  The speed rating can be found near the size on the sidewall of the tires and will typically be a letter G(56mph), J(62mph), K(68mph), or L(75mph).   To save some stress down the road, make sure you know your trailer tire speed rating before you hit the highway.

Load Range

The load range is the load carrying capacity or weight capacity of your tires.  Similar to speed ratings, load ratings are a letter rating found on the sidewall of the tire. The further the letter is in the alphabet, the greater the weight limit will be.  ST trailer tire load range ratings are generally B, C or D. B is the lightest load range capacity and E is the heaviest load range classification. If your trailer tire is a C Range tire, it can carry 1,820 lbs, so this means on a single axle trailer it can carry 3,640 lbs. Keep in mind that going to a higher load range tire will not increase the load range of the trailer.

Where do I find the tire size for my trailer?  Every trailer comes with a placard with tire size, load capacity, GVWR, VIN#, etc.  It is usually found near the front of the trailer. 

What is the most common trailer tire size?  A 225/75-15 tire is a pretty typical size for trailer tires, but check your trailer or owner’s manual to find out what tire size is compatible with your trailer. 

How much do trailer tires cost?  Trailer tires cost anywhere from $70 to $150 each.  It depends on the size, type, and quality.  Of course, a better quality tire will cost more but typically lasts longer.

Can I put car or truck tires on my trailer? Never put car tires on your trailer, the sidewalls are not strong enough to carry a load.  You may be able to get by with an LT or truck tire on your trailer, but typically ST tires are best for trailer hauling.

How long should my trailer tires last?  Typically trailer tires last 3-5 years, but you’ll be doing good if you get 30,000 miles out of them.  This seems like a drastic difference compared to car tires which easily get anywhere from 50,000 to 80,000 miles.  This is because trailers aren’t used as often as your car or SUV.  Chances are your boat trailer only goes to the lake several times during the summer and sits around the rest of the year. Most likely it is sitting outside with the sun beating down on it all summer and the cold and snow blowing around it all winter.  All this sitting is not good for tires and causes them to wear out prematurely. 

How can I make my trailer tires last longer?  Inspect your trailer tires regularly. A worn-out tire is a safety issue and can be very dangerous if it blows out, especially at high speeds.  Keep the air pressure at the maximum PSI for your tires. If storing your trailer inside is not an option, consider getting tire covers to protect them from sunlight.  Simple maintenance items like rotating the tires, and a wheel alignment go a long way in making your trailer tires last longer.    

What is the difference between D vs. R trailer tires?  The D in a tire size of ST205/75D15 stands for bias ply and if you see the letter R in the tire size where the D is, that is a Radial tire.

Who sells trailer tires in Des Moines?    All Hilltop Tire Service locations in Des Moines have a large inventory of ST trailer tires.  When you’re ready to replace your trailer tires, our trailer tire experts will be able to get the right tires for your hauling needs.

We are a Trailer parts and Accessories Superstore

Buying trailer tires can be an overwhelming task, but rest assured, we are here to help with all your trailer needs. Not only do we have a large inventory of trailer tires and parts, but our certified technicians are also trained to repair and maintain trailers as well.  From axles to hitches, and everything in between, we’re here for you and your trailer!