How to Choose the Right Trailer Tires: A Calgary Towing Guide

In Calgary, trailer season runs from the first long weekend to the last. Boats to Ghost Lake, campers to Kananaskis, utility trailers loaded with gravel or a season's worth of yard work — and every one of them rides on tires that get ignored until one lets go on the shoulder of the QE2. Choosing the right trailer tires up front is what keeps that from happening.

Trailer tires aren't just smaller car tires. They're built differently and they fail differently. Here's how to choose the right ones for what you tow.

The short version

• Match the tires' total load capacity to your loaded trailer weight, with margin to spare.
• Use ST (Special Trailer) tires — not passenger (P) or light-truck (LT) tires.
• Pick the right load range (B, C, D, E) for the weight you carry.
• Trailer tires usually age out before they wear out — replace them by 5–6 years regardless of tread.

1. Start with your trailer's weight

Everything begins with weight. Find your trailer's GVWR (gross vehicle weight rating) on its data plate, then think about what you actually load into it. The combined load rating of all the trailer's tires needs to comfortably exceed that fully-loaded weight. If you tow near your trailer's limit — gravel, firewood, a side-by-side — you want margin, not a tire that's maxed out on every trip. Overloaded trailer tires build heat, and heat is what kills them.

2. Understand load range and ply rating

Trailer tires are graded by load range — B, C, D, or E — which is the modern version of the old ply rating. Higher letters carry more weight: load range C is roughly a 6-ply equivalent, D is 8-ply, E is 10-ply. The right load range depends on your trailer's weight, not on going as high as possible. Our companion guide on trailer tires and load ranges breaks down exactly how to read them, and load index for towing in Alberta covers the numbers on the sidewall.

3. Use ST (Special Trailer) tires

This is the one most people get wrong. Trailer tires are marked ST for Special Trailer, and they're built for the job: stiffer sidewalls to resist sway and the side loads of cornering, and a construction designed to carry weight rather than drive or steer. Passenger (P) and light-truck (LT) tires aren't built for trailer duty and shouldn't be substituted unless your trailer's manufacturer specifically allows it. An ST tire keeps the trailer tracking straight behind you instead of wandering.

4. Radial vs bias-ply

You'll see both. Radial ST tires run cooler, last longer, and ride smoother — the better choice for highway towing and the long hauls to the mountains or BC. Bias-ply tires are cheaper and have stiff sidewalls that resist damage, which can suit short, local, heavy-haul trailers that don't see much highway. For most Calgary drivers towing any real distance, radial is worth it.

5. Get the size right

Match the size already on your trailer (or the manufacturer's spec) unless you have a good reason and the load math to change it. A trailer tire size looks like ST225/75R15 — the same format as a car tire, with ST in front. If those numbers look like code, our guide on how to read a tire size decodes them. The wrong size changes the load capacity and the ride height, and can throw off how the trailer follows your truck.

6. Don't ignore tire age

Here's the trap with trailer tires: they almost always age out before they wear out. A trailer sits for months, bakes in the Alberta sun, and the rubber dries and cracks long before the tread is gone. Plenty of trailer-tire blowouts happen on tires with lots of tread but six-plus years of age. Check the DOT date code and plan to replace ST tires around the 5–6 year mark regardless of how they look, sooner if you see sidewall cracking.

7. Keep them maintained

Trailer tires reward a little attention. Inflate them to the maximum cold pressure listed on the sidewall — unlike a car, a trailer tire is designed to run at that figure. Check the pressure before every big trip, because a slow leak on a parked trailer goes unnoticed. Inspect for cracks and flat spots after winter storage, and keep the trailer off direct sun or use covers when it's parked for the season. Our tire maintenance guide covers the basics.

Trailer tires we stock in Calgary

We carry ST radial trailer tires across the common load ranges, plus complete trailer tire-and-wheel assemblies if you'd rather swap the whole unit. Browse trailer tires or complete wheel assemblies online, and if you're not sure what your trailer needs, our guide on where to find trailer tires in Calgary points you in the right direction. We price-match any legitimate local quote.

Frequently asked questions

Can I use regular car or truck tires on my trailer?

It's not recommended. Trailer tires are marked ST (Special Trailer) and built with stiffer sidewalls for towing loads and resisting sway. Passenger or light-truck tires shouldn't be used unless your trailer manufacturer specifically allows it.

How long do trailer tires last?

Usually 5–6 years, and often the rubber ages out before the tread wears out. Sun, ozone, and sitting unused all age trailer tires, so check the DOT date and watch for sidewall cracking rather than relying on tread depth alone.

What load range do I need for my trailer?

It depends on your trailer's loaded weight. The combined capacity of the tires should comfortably exceed the trailer's GVWR. Load range C, D, or E covers most trailers — bring your trailer's specs and we'll match it.

What pressure should trailer tires run at?

The maximum cold pressure printed on the sidewall. Unlike a car tire, a trailer tire is designed to run at its max rated pressure to carry the load and run cool. Always check it cold, before towing.

Are radial or bias-ply trailer tires better?

For highway towing and longer trips, radial tires run cooler and last longer. Bias-ply tires are cheaper and very rugged, which can suit short, local, heavy-haul use. Most Calgary drivers towing any distance are better off with radials.

Where can I buy trailer tires in Calgary?

At Prince Tires — we stock ST radial trailer tires and complete wheel assemblies, and we'll help you match the right load range and size. Browse online at princetires.ca/collections/trailer-tires or call (403) 452-4283.

Getting your trailer ready for the season? Bring it by or call and we'll set you up with the right tires. Prince Tires · 111 42 Ave SW, Calgary, AB T2G 0A4 · (403) 452-4283 · Book online.

Posted by the Prince Tires team. Calgary tire specialists since 2021. Last updated: June 2026.

Sources: Transport Canada, Tire and Rubber Association of Canada.