Trailer Tires? or Automotive Tires?
The topic of trailer tires has come up a hundred times. Why can’t I use automotive tires on my trailer?
I’ve actually asked many trailer parts stores (and tire stores) the same question just to hear their response. Most are quite adamant that only trailer specific tires should be used on trailers. Others are a little more humble and admit they don’t really know why. Only a few can really articulate the why’s of choosing a tire specific for your trailer.
I’m not the expert, by any means. I’ve designed a bunch of things in my life, but never a tire. Take that for what it is, because I’ve talked to a lot of tire experts and here’s how I come down on the issues.
- First, they make trailer tires for a reason, and it’s not just to get more money out of you.
- Second, anyone that says trailer tires experience more crazy loads and dynamics than autos are not thinking clearly.
- Third, trailers DON’T have inherently more trouble with tires than cars.
We’ll discuss these in a moment, but let’s set the stage. Tires are really important for a number of reasons, and tire problems have haunted trailer owners for years. The above 3 items really address some folklore laced with experience rather than complete facts. There are arguments on both sides, so I’ll layout some facts, then you put them together to fit your needs.
First, why Trailer Tires?
The design of trailer tires is not superior nor more technologically capable for hauling than automotive — in fact, it’s the opposite. There is a ton more technology in auto and light truck tires, and there’s way more of them around.
That said, there are several advantages in using trailer tires:
- They have the advantage in load capacity for the size. (Smaller total size, greater capacity.)
- The narrow form factor allows more space (from left side of the trailer to right side of the trailer) between tires for the same outside trailer width. That allows trailer designers to maximize the frame and load area between the tires. (More space between the wheel wells for utility trailers.)
- Narrower profile tires (like trailer tires) wear better when not aligned properly. (And this is a frequent problem with trailers that are not set-up properly — especially for multi-axle trailers.)
- Trailer specific tires are also better at resisting damage, neglect and abuse (because they’re really tough). See the ply ratings.
- Automotive suspensions are nicer to loaded tires than trailer suspensions, so the beefier trailer tires tend to soak up the abuse better.
- Stiffer side walls resist tipping more for trailers with a high center of gravity. (Though this is really an excuse or a compensation for poorly loading a trailer.)
Why Automotive or Light Truck (LT) Tires?
- Automotive tires have a wider range of available sizes and capacities (except in the really small sizes).
- They come in more weight capacities and material choices (to optimize for your needs).
- They typically ride much better, track better (if the trailer is built well and loaded properly).
- Automotive tires usually have a larger footprint on the road (especially useful in soft conditions like on the lawn).
- Trailer tires are not as available when you desperately need one, nor do they interchange on your tow vehicle.
- Lower pressures make it easier on equipment, and easier to see when one is getting a little low.
- See the discussion below about dynamic loading.
The Dynamics of Tire Use:
One big error … Some people claim that trailer tires can handle greater dynamic loads, and do better. This is not true. It may seem that way because there are more trailer tire problems per tire than automotive, but the ability to handle loading is NOT the reason. Automotive tires are designed for high, simultaneous, steering, breaking and weight shifting loads. They have to be to take what we do to them. Think about your left front tire in a hard right turn when you’re hard on the brakes! Trailer tires don’t / won’t perform at anywhere near that level. Rightfully so, because they just don’t see those kinds of extremes in action.
Please remember, this is all in context of similar tire capacity.
Two places a that tires on a trailer do see a different type of dynamic:
- First, if a trailer is loaded improperly, or set-up is poor (axle position or alignment not correct), the trailer may wander side to side — like a dog wagging it’s tail. See this video for an example. These are not high loads, so both trailer and automotive tires do OK, but it’s not good for either.
- Second, when a trailer is virtually empty, they can bounce as the encounter bumps. The bouncing can be mitigated in a few ways, but tire pressure is the main player. This post talks all about trailer bounce. There are good arguments that trailer specific tires handle bouncing a touch better, though automotive tires are better at mitigating the effect.
Trailer Tires DON’T Have Inherently More Trouble:
The other side of the coin is how we contribute. I just stated above that “there are more trailer tire problems per tire than automotive” but that does NOT mean it’s the inherent nature of a tire on a trailer. Rather, it’s because we tend to be lazier and more neglectful with our trailers than our cars.
Again, looking at loading: On your vehicle, the tires are typically at a much lower percentage of total capacity than for most trailers. And we typically don’t take as good of care of them. You drive your vehicle frequently, so the tires usually wear out before having trouble like flat spots, dry rot, carbon leaching, etc..
Another thing is our sense of the tire. In your car, if the alignment gets bad, you notice it. If your trailer tires are not aligned or balanced or properly inflated, you probably won’t notice unless it’s really bad.
So why are there more problems with trailer tires? Because we (collectively) don’t take care of them.
The folks at Tire Rack argue for using only trailer tires, but it’s interesting that all of the reasons they give are just a compensation for the things discussed above — like reducing load capacity 9%. I assert — If the tires are the right size, properly aligned, and not overloaded — AND if we take care of them — automotive tires on a trailer will perform great, and in most cases, even better than trailer specific tires. The exceptions are, of course, applications that need small tires (they don’t make automotive tires in those sizes). And, for applications that need the really high capacity tires. Otherwise, I prefer light truck tires over trailer specific ones any day.
Then there’s the discussion of Radial vs. Bias Ply. I’ll let you research that.
Let us know if you have comments or suggestions.