When Does A Trailer Need Brakes?

There are laws that say when a trailer must have brakes.  In most places within the USA, when the trailer total capacity is over 3000 lbs, trailer brakes are required.  That is all well and good, but we all know that laws are an ignorant way of covering the least common denominator.  So, are there better guidelines?

In practice, the better guidelines don’t exist.  However, this article considers several other things to think about.  These are not rules, or laws, but they are guiding principles.  Please note, some “Rules of Thumb” are conflicting, so this article is to open eyes, not to give strict rules.

Again, we are NOT talking about the total your vehicle can tow, we are talking how much WITHOUT trailer brakes.  For info about total towing capacity, read the article How Much Can I Tow With My Vehicle?

What’s the Big Deal?

Nearly every axle you can buy comes with an option to add brakes.  For the most part these are like the drum brakes of older cars.  (See the photo.)  The technology has been around for a long time, so it is well proven, and generally quite effective.  It looks kind of complicated, but it is really not.

There are other styles like disk brakes too, but they are not as common.  There are also various ways to activate them.  The drum break shown is electrically actuated (electricity activates the brakes).  There are other types of activation too, like Hydraulics, or air.  But, those don’t really matter to the main question of this article.

Anyway, the type of brakes does not matter so much as if they are there and hooked up.  That is the first job.

Weight Ratios

The need for trailer brakes really comes down to one thing – how much do you want to slow down?  Some people might ask instead – do you want to stop?  But brakes are for a lot more than just stopping.  In fact, the worst conditions for brakes are not stopping, but trying to control speed down a hill.

With that in mind, how good are the brakes on your tow vehicle?  How much weight does your car manufacturer think they can appropriately stop?

I have heard some guidance as weight of the tow vehicle compared to weight of the trailer.  If you are going to use that concept, then you need trailer brakes if the trailer is more than 50% of the weight of your tower.  That is a pretty easy guide, but . . .  Try stopping 50% extra weight – especially when that weight is not on the vehicle wheels assisting with the downward force that helps braking.

I don’t really like this guidance as it ignores some other important factors.

GVWR

Another way to think about it is in terms of GVWR (Gross Vehicle Weight Rating).  This is based on braking ability.  Granted, the trailer weight is not on the tow vehicle, but without trailer brakes, the vehicle must stop that weight too.  If we think in terms of what the manufacturer says, presumably the vehicle can stop that much weight.

This guideline says – you need trailer brakes if the weight of your vehicle + all cargo + trailer is greater than the GVWR.  So, if your mid-size SUV has a GVWR = 7,500 lbs, and you have the vehicle, 4 passengers with all their gear adding up to 6,000 lbs, then you can tow a 1,500 lbs trailer without trailer brakes.  (These numbers are improv only.)

In this example, if we look at the legal limit of 3,000 lbs for a trailer without trailer brakes, we see that puts the overall system into a questionable situation.  Even though specs for the SUV say it can tow 3,000 lbs, without knowing more about the braking system of the SUV, this situation is very likely big trouble.

Again, this is not super scientific since it does not take all the details into account.  However, as a general guideline, I like this GVWR approach much better.

Yes, there is the little factor of weight on the wheels to provide more traction, versus weight of the trailer which does not provide more traction.  Yes, skidding when trying to stop fast is a big deal when pulling a trailer that does not have brakes.  That is a limitation of this approach, but as a rule of thumb, it is better than the 2 above.

Trailer Brakes Determination By Sampling

Try it.  If you are wondering about brakes, hook trailer to your vehicle and drive a little.  See how fast it stops.  Check out how much added distance you need with the trailer (versus driving the vehicle without the trailer).  Start slow, then gradually faster.  If it surprises you about how much more it takes to stop things, then get the trailer brakes hooked up.  OR, If you can’t hardly tell, then you might not need trailer brakes.

On the other hand, if stopping or braking – especially into a corner – ever scares you – even just a little – then, go hook up some brakes.  The size of the trailer does not matter.  If something about stopping has you worried, then get brakes.  That is especially true if the trailer is heavier than the tow vehicle.

See this other article about tandem axle brakes – versus one brake axle and one idler.

Caveats in Choosing Trailer Brakes – or Not

There are definitely some environmental factors in the decision too.  Here is a list of additional decision makers.

• For driving in the mountains, bias your decisions FOR trailer brakes.  You definitely don’t want to end up needing one of those run-away truck ramps.
• If you will drive fast, again, brakes are more important.
• For long distances, bias your decisions FOR trailer brakes.
• When roads are less than ideal – rain, snow, ice, mud – having more points of braking contact is usually better.
• If your vehicle is basically empty, and the trailer is basically full.
• When you are near the GVWR, bias toward having trailer brakes.
• Finally, longer trailers can benefit more from brakes.  The longer the trailer, the more dynamics effect things, so brakes become even more helpful.

This is where the “Common Sense” comes in.  Unfortunately, Common Sense is not so common, so take this for what it is worth, and don’t be Cinderella’s sister.  If the shoe does not fit, go find the right shoe.

I have done it, and fortunately lived to tell.  For kicks, here is a silly story – from younger, dumber times.

Easy Does It

When I was in college, I drove an early VW Rabbit.  A great little 4-cylinder economy car.  I did some work on the engine including a switch to a multi-stage carburetor so the little VW was quick with get up and go.  The car weighed roughly 2800 lbs empty, and it had a tow rating of zero.  Seriously, the owner’s manual said you must not pull a trailer with it.  Note:  Bolstering the engine does nothing for the brakes.

I also had a 20′, long, thin trailer for towing a racing motorcycle and associated gear.  Guess what pulled the trailer?

Yes, I welded up a nice hitch for the VW, and I pulled a trailer around that weighted more than the car (a little more).  Young and dumb?  We can go with that, but as an Engineering student as well as a mechanic, I looked beyond the mark in thinking it was safe.  Dumb luck is more the truth.  It worked out, but I will admit, “Easy Does It” ruled the day.  I endangered so many people with that contraption.  The hitch was great, but I didn’t ever take the time to hook up the trailer brakes.

I don’t recommend the approach to anyone.

Trailer Brakes at 3000 Lbs.

I am a fan of brakes.  With small, light trailers it does not matter so much.  Yet, there are limits.  My FIRST big advise is:  Consider what you are doing, and think about how you would respond if someone driving your rig was following your daughter (just learning to drive).  Would you want them to have trailer brakes?  If you are good with it, then perhaps it passes the sanity test.

The SECOND piece of advise:  Yes, make sure you meet the legal limit with trailer brakes for anything over 3,000 GTW, but go a step further.  Figure out what the real numbers are for your rig.  For any vehicle smaller than full-size, it is certainly a good bet that towing at the 3000 lbs legal requirement is pushing the limits.  Be smart.

And THIRD, many (most) jurisdictions have extra requirements for trailers over 3000 lbs, like installing a Breakaway Kit.  Good to know if you use a trailer in one of those places.

Safe Towing To You!

For a little more information about trailer brakes and safety measures, try our “Where’s Waldo” Trailer Safety Game and, of course the following Answers Article.