Does My Trailer Need A Spare Tire?

What about that trailer spare tire?  No, I don’t mean the one around my middle . . . for your trailer.  Do you really need one?  Some say yes, and we see them on many trailers, but they are rarely used.  What if you just go without?

These are great questions — and we do see a lot of trailer “spare tires” that just dry-rot in place.  If they are actually needed, they might not function anyway.  So, . . .

How Important Is A Spare Tire?

The answer to this question comes best by thinking about how you use the trailer.  If the trailer is rarely used, especially if it is stored in the sun where dry-rot is an issue, then a “good” spare is probably very important.  Dry-rot and other issues that stem from infrequent use are the plague of trailers.

(Keep in mind that these same issues can affect the spare tire too, so having a spare in bad shape – or flat – might be the same as not having one.)

On the other hand, if you carefully inspect the trailer before use, keep the tires in good shape and have a good road-side assistance program, a spare may not be needed.  Yet, if you’re the kind of person that keeps things up, then you’re probably the kind of person that likes the extra assurance of having a spare tire.

There is one other point . . . one method of efficiency that works.  When the same size wheels and tires are on both the trailer and the tow vehicle, then just the vehicle spare will accomplish the task for any of the wheels.  (I did this for a lot of years.  Unfortunately, it doesn’t work for my current setup.)  If this works for you, then it accomplishes both situations.

When A Spare Is Necessary

From a personal standpoint, in all the years I’ve pulled a trailer, I have only needed a spare once.  Fortunately, it was the same size as the tow vehicle, but then I had two.  That really made me wonder why?

Looking at the scenarios above, both suggest that a spare is likely, or desired.  In truth, we occasionally see trailers alongside the highway with tire issues.  And it’s worth saying — tire issue are big with trailers.  Yet, they don’t have to be.

Some of the folks I’ve stopped to help had a flat spare.  Some didn’t have a spare tire.  Almost all were violating one of the big rules of trailer towing.  Here are the 3 reasons I see that cause tire trouble on trailers the most:

1. Neglected Tires.  Dry-rot, underinflation, age, etc..  Note, underinflation does not mean lower pressure for bounce and stability.  Choose pressure carefully, and maintain it.
2. Overloaded Tires.  Exceeding the tire capacity is asking for trouble, and many people find it.  We recommend tires with at least 10% over capacity, because tires are not perfect, and neither are the roads we drive on.
3. Axle Issues.  This can include torsion axles in tandem or triple, or trailer attitude (again, multiple axles), or non-aligned axles, or brakes that rub enough that the tires get really warm, or poorly mounted axles, bent axles, etc.

One other reason for wheel problems is neglect of bearings and lubrication, especially with boats, but that’s another topic.

In my experience, if the trailer and tires are in good condition, have proper inflation, and are well within the load capacity, there are not many problems.  So does that mean you don’t need a spare tire?

Our Recommendation

The Down Sides of having a spare include:

1. Cost (possibly for something you will never use).
2. Weight (it adds weight to the trailer that you have to lug everywhere you go).
3. Location (you have to put it somewhere).
4. Hassle (because it’s one more thing to maintain).

There are only two real Up-Sides to having a spare.

1. If you ever need it, you won’t be stranded (like this one).
2. Peace of mind knowing you have one if needed.

The down sides are certainly something to consider, and only you can make the decision.  However, our recommendation is:  Carry a Spare Tire.  The up-Sides are just too compelling, and the down sides are not that bad.  I’ve seen trailers left on the side of the road without a wheel — presumably because of a flat or blow-out.  I don’t want that kind of hassle!

I suppose one more thought with the decision is how often you care for your tires.  Do you keep them in tip top shape?  Here is some more info on when to replace trailer tires.

What Trailer Tire?

Then comes the question of what tires to use (and we have a whole article on Wheels and Tires if you want).  The ideal choice is to have the spare tire match the others, then rotate tires, including the spare, every few thousand miles.  That can be a hassle in itself, so the next best choice is to have the spare (perhaps a cheaper tire) and skip the rotating.

Must I always use trailer specific tires on my trailer?  Or can I use light truck tires?  Or are there other options I should consider?

These questions are in the linked post, but the short answer is — use nice radial tires for the main trailer wheels, then a narrower (probably hard) trailer specific tire for the spare.  That makes it easier to store.

It’s like the doughnut spares they put in cars.  Treat it like a temporary tire for emergencies.

Where Do I Put A Spare Tire?

OK, so we recommend a spare tire, but where should it be stored?  The ideal place is out of the sun.  That might mean under the trailer, or with a cover of some sort.  There are a few pictures here that show how others mount their spare tire.  We think it’s a good idea to put it in a place where it’s both out of the way, and convenient to check the tire pressure.  AND, out of the sun.

Spare Tire Emphasis:  Unlike the images on this page, it is much better to keep the spare tire covered (protected from the sun) to avoid dry rot.

I personally like the spare tire hidden under the trailer because it’s completely out of the way.  The down sides are:  1) it can also be out of mind;  2) it’s harder to check, and 3) sometimes also harder to access if you need it.  I like to hang the spare under the trailer deck just in front of the axles, or under the tongue if it’s conveniently covered.

For an example with a 5th wheel trailer, try this article with several good trailer ideas.  The spot of the spare is great for using space efficiently, but probably hard to access, and it is not covered.  Worth thinking about the ideas.

Wherever you choose to put it, just don’t forget to check it every time, just as you also check the other tires.