Hearing that thumping while driving in your tow vehicle is an unpleasant sound. As you pull over, you must deal with a flat tire on your trailer. Hopefully, you have a spare tire!
Tire failure on a trailer is common; we usually see someone on the side of the freeway with a flat tire. But what happens if you do not have a spare tire? Can you continue to drive your tandem axle on the remaining 3 tires? The right answer does vary, and the risk level also can change based on your conditions.
This post will review you can drive a dual-axle trailer with 3 tires. However, there is a safety risk and potential damage to your trailer. This post will review the following:
- Trailer Weight
- Trailer Axle
- Trailer Tire
- Wheel Bearings
- Trailer Brakes
Whether you have a utility trailer, travel trailer, or boat trailer, the same principles and applications all apply.
Below is a quick summary of what trailer components will be affected by towing a dual-axle trailer on 3 tires.
|Trailer Weight||Gross Vehicle Rate||Exceed by 25%|
|Trailer Axle||Added stress and strain||Adds 50% strain|
|Trailer Tires||Added weight to remaining tires||Exceed load rating by 33%|
|Wheel Bearings||Added stress and heat||Adds 50% stress|
|Trailer Brakes||Adds heat and reduced power||Lose over 25% stopping power|
Table of Contents
- Trailer Weight
- Trailer Axle
- Trailer Tire
- Tire pressure
- Wheel Bearing
- Trailer Brakes
- Final Thoughts
As we review the issues of driving with 3 tires, one of the main things to consider is the trailer weight. As the load weight increases, those heavy loads increase your chances of running into more problems with only 3 tires.
The gross vehicle weight of utility trailers is based on towing as designed, with 4 tires. You have reduced your towing capacity by 25% when you lose one of the tires. So if your gross vehicle weight of the trailer was 4,000 lbs, now you just reduced it to 3,000 lbs. And if you had a load weight of 3,500 lbs before the flat tire, you are exceeding the trailer rating. As we will discuss, this will add much more stress and safety concerns.
One of the advantages of a dual axle trailer (also known as a tandem axle) over a single axle trailer is that you have 4 tires that help with load weight and trailer sway. They are more stable overall and distribute the weight better to two axles instead of one.
Each trailer axle has two ends, with brakes, bearings, and some connection or suspension. The axle is designed to hold the trailer tires in place and distribute the weight that the load carries. When you have all 4 tires working, the trailer axle is working as designed, with no added stress that it was not designed for. A missing tire not on the ground to hold one-half of the axle load adds TWICE as much stress to the axle as intended.
Towing with only 3 tires will add stress to your axle and potentially bend or crack the axle.
Your trailer tire is the most important part of your trailer. This is where the rubber meets the road. It is how your trailer connects and moves around on the ground. And now that you only have 3 out of 4 tires puts you in a bad spot to efficiently and safely move about.
The first thing to know is that your trailer tires are not the same as your car’s radial tires. Trailer tires are designated as ST tires or Special Trailer tires. They are designed and tested to meet the specific conditions of a travel trailer or utility trailer.
Tire tread on ST tires is designed more for how the trailer is being towed and how it will sway more. This helps with tire wear and the longevity of the tire.
Tire pressure is critical to trailer safety and its load-carrying capacity. Checking your tire pressure before each trip is one of the most important things you can do when towing your tandem axle trailer.
Your travel trailer or utility trailer usually has a sticker indicating tire size and recommended tire inflation. Usually, trailer tires have higher pressure to get the load capacity they are looking for. It is not uncommon to see a trailer tire manufacturer recommend 60 psi or more. This is one of the reasons that trailer tires are known to have issues, as their high pressure makes them easier to blow or get flat.
When you reduce your tires from 4 to 3, you are putting extra weight onto the remaining tires. Let’s use the example again of a 4,000 lbs trailer. If your trailer is rated at 4,000 lbs, the axles and the tires were tested at that maximum number. Tire speed (highway travel) and heat (summer) are all factored into a manufacturer saying this is their gross vehicle weight.
Losing one tire now adds weight to the remaining tires that they are not designed to handle. Losing one tire, at 1,000 lbs, puts an extra 333 lbs to each tire. If those tires are not rated for 1,333 lbs and have a heavy load, you increase your chances of having another flat tire.
Part of your tires and wheel concerns are the wheel bearings and what damage that can happen to them. These tiny pins or ball bearings spin thousands of times a minute. They are your only moving connection from the axle to your wheel.
When you reduce your trailer to 3 wheels only, you have put an additional 50% load strain onto the wheel bearing with the missing tire. This additional load and strain on the wheel bearings will cause additional heat and the potential for failure, especially at high speeds to the remaining tire.
For more information, visit the post on trailer bearings.
Lastly, there will be an issue with your trailer brakes and stopping ability. Trailer brakes work by slowing down or stopping a drum rotor or disc brake. The drum brake is connected to the trailer wheel, slowing down its road rotation.
With a tire missing, you lose the stopping power the brake provides. Even the brakes work fine and are slowing down the drum. Without that stopping power transferring to the wheel and tire, it’s essentially doing nothing to help you stop.
By only having 3 tires, you reduce your braking capacity by more than 25%! Why more than 25% if this is just one out of four? The reason is that the opposite brake on the same axle is now doing DOUBLE the work to stop. That additional stopping and heat generated will cause brake fade and reduce that brake’s performance.
Knowing this, it is critical to your safety to provide additional time for stopping and reduce speed to allow for the lost power of the braking system.
Yes, you can drive a dual axle trailer with 3 tires, but there are some cautions and the potential of further damage. Your trailer axle and wheel bearings will get added stress and strain with potential permanent damage. And you will also increase your risk of another tire blowing because you are increasing the remaining tire loads by 33%. Finally, your braking power is reduced by over 25% since no wheel and tire can transfer that stopping power to the ground. Keep your speeds low, and see about getting a spare tire on as soon as possible. Safe travels!
Tony is an avid camper and RV traveler. He fell in love with camping on his first RV trip with his wife over 25 years ago. Tony loves sharing lessons learned and tips about RV maintenance and safe traveling.