Trailer Tires vs Car Tires: How to Choose the Right One
Why Choosing the Right Tires is Critical
2024 has been the year of the tire for the Our Campfire Unplugged crew! We have put tires on every vehicle we own: RV Fifth Wheel, Silverado 3500 (tow vehicle), and some passenger cars. Like you, when we invest our hard-earned money, we want to get the best value for our dollars!
So, we researched the heck out of all the tires we purchased and want to share this with you!
When spending upwards of $200 to $250 per tire or over $1,000 for a set, trailer owners need to understand the difference between trailer tires vs. car tires. Taking time to understand the types of tires will help you avoid problems during your RV trips!
Trailer Tires (ST) vs. Passenger Car Tires (P)
Before heading off to the tire shop or online to Tire Rack let’s cover some basic terms you will encounter. Trailer tires are often referred to as “ST” or Special Trailer tires. All this means is the tire is specifically designed for a trailer.
Is it important to use ST Tires? In short, yes!
Passenger Car Tires are often referred to as “P” tires. You may also encounter “LT” or “AT” tires which are Light Truck and All Terrain tires. Light Truck tires are designed for heavier duty trucks like 250s/2500s or 350s/3500s and some heavier duty SUVs. While All Terrain tires are geared more for off-road enthusiasts or guys who lift their trucks!
The quick takeaway is ST Tires are specifically designed for trailer use and support the heavier loads of your trailer, RV travel trailer or fifth wheel. Passenger Car Tires and Light Truck tires are designed for cars and trucks and often lack the sidewall strength needed for RV travel trailers and fifth wheels!
ST Tires: What Sets Them Apart
Trailer Tires are specifically designed to carry heavier loads, resist tire problems like sidewall flexing, and effectively deal with the heat generated traveling at highway speeds! ST tires have very stiff sidewalls which allows these tires to perform well with a very heavy load like an RV travel trailer.
Passenger Car Tires: Where They Fall Short
Tires designed for passenger vehicles and light trucks often fall short of handling the heavier loads associated with travel trailers and fifth wheels. This is because passenger car tires are designed to handle a wide number of environments.
For instance, car tires and LT tires must be able to handle the torque associated with acceleration, braking, turning, traction control in the rain, and holding the weight of the vehicle. These tires are built with softer rubber compounds and are generally rated lower (e.g., lower ply) than ST tires.
Using regular tires (e.g., car tires or light truck tires) on your trailer can result in safety issues!
ST Tires: A Breakdown
Choosing the proper tires is the first step to avoiding a costly breakdown or blowout. A blowout can turn a good day to a bad day in a hurry!
Thicker Sidewalls for Stability
ST tires have more rigid sidewalls. Removing the flex from the sidewall means the ride is rougher, but it helps eliminate the “wiggle” in your tire which helps reduce trailer sway. Trailer sway can be especially dangerous at any speed and incredibly dangerous on the highway!
Stiffer sidewalls also helps the tire track more straight which means greater efficiency and control over your travel trailer or fifth wheel!
Rigid sidewalls help hold the load without the tire collapsing. If the tire is bouncing because the sidewall is weak or the air pressure is low, heat can build up and heat causes numerous problems for tires.
Heat causes the tread to separate from the tire which makes for a really bad day and it can cause a blowout of the tire!
Better Heat Resistance for Long Trips
ST Tires were designed to manage heat on long trips. The resistance from the road and carrying a heavier load causes heat to build in the tire. Trailer tires are designed with less deep, non-skid tread, which means less rolling resistance and allows for better heat dissipation vs. car tires!
The Downside of Using Passenger Car Tires for Trailers
One of the biggest downsides to using Passenger Car Tires or Light Truck tires for a travel trailer or Fifth Wheel is load capacity. According to RVSafety.com the same size tire load can range from 1,800 pounds for a passenger tire to 2,500 pounds for a ST tire!
- “Passenger Car Tire – P225/75R15 can carry 1874 lbs.
- Light Truck Tire – LT225/75R15D can carry 2205 lbs.
- Special Trailer Tire – ST225/75R15D can carry 2540 lbs” (from RV Safety
Trailer owners using the wrong tires face increased risks of tire problems like blowouts, tread separation, premature failure, poor treadwear, improper handling, etc.
The lower cost of passenger tires may be appealing, but the potential problems are not worth the risk!
Weight & Load Issues
Do you ever feel like all the weights, measurements, letters, numbers, etc. are needlessly confusing? Me too!
But, these data points are crucial for safe operations!
On passenger and light truck tires the load index is stated as number on the tire’s sidewall. The load index ranges from 75 (carry capacity 875 pounds per tire) to 150 (7,385 pounds per tire!).
A passenger car tire will carry one load index. While a light truck tire carries two load index. For example a LT tire load index may be 144/141 which means a single rear wheel truck (SRW) can carry 6,173 pounds while a dual real wheel truck (DRW) can carry 5,677. That seems odd right? It’s because if a tire on a DRW fails you want the other tires to carry the load.
Trailer tires state load index with letters where A is the lowest index with a ply rating of 2 while an N is the heaviest with 24 ply rating.
Did You Know: A ST Tire capacity can be up to 10% more than the same LT tire?
Reduced Safety
As RV owners, we are all concerned about safety. We want our family and our equipment to arrive safely at our final destination, and we want to make sure we are operating safely for other motorists on the road!
Regular tires lack the stiffer sidewalls of ST tires. This leads to swaying and potential accident. In addition, heat can build up which can lead to blowouts!
If you experience a blowout on a dual axle or triple axle trailer you should consider replacing all tires on that side of the trailer. This is because the other tires had to step up and carry the load. These tires could be damaged from the additional stress!
Tire Pressure Monitoring Systems
Many RVers use Tire Pressure Monitoring Systems (TPMS) to get real time statistics on their tires. TPMS share information about the tire pressure and internal temperature. Sudden changes, drops in air pressure or spikes in temperature, mean trouble. Alert RVers can pull over and avoid a potentially dangerous situation.
When using TPMS make sure to use metal valve stems. This may mean a trip to the local tire shop to have metal valve stems installed! Failing to do this may lead to a blowout…don’t ask how I know that!
Since most signs of tire trouble come after the tread is flapping around the tire or smoke is pouring from the tire, a TPMS can really be the difference between a good day and a bad day!
Like all equipment, make sure you carefully study the manual and operating instructions. Don’t just wing it with safety items!
Tire Size and Load Capacity
The sidewall of the tire contains important information about the tire size and load capacity. Always refer to the recommendations from your trailer manufacturer. For instance, if you upgrade from 10 ply ST tires to 12 ply or 14 ply ST tires, make sure the trailers wheels can handle the added air pressure (PSI) of these tires. Heavy duty tires operating at less than stated air pressure can create a blowout or worse!
Trailer Tire Sizes
When choosing replacement tires for your travel trailer, make sure the tire size matches your trailer’s load requirements. Failure to match the load requirements could lead to all sorts of problems.
We replaced the tires on our Keystone Cougar 364 with thicker ply tires (14 ply). The ride is definitely stiff for our camper. Every trip the cushions on the dinette bounce off! Still I felt better going up to 14 ply vs 10 or 12 ply!
Load Capacity and Safety
ST tires are designed to support the heavier loads of travel trailers and fifth wheels. The rubber compounds more rigid than passenger tires which makes ST tires the safer choice for your trailer.
When evaluating replacement tires RV owners need to consider the load capacity of the replacement tires. Many RVers swear by Goodyear Endurance tires. Goodyear makes great tires. However, for our Keystone Cougar the maximum load range for these tires is “E” which is ply equivalent to 10. We selected Sailun ST tires with a load range “G” which is the ply equivalent to 14! This felt like an added margin of safety for our fifth wheel!
Radial vs. Bias Ply Tires: Which is Better?
When it comes to choosing the right tire for your trailer, understanding the difference between radial and bias ply tires can help you make a smarter choice for your towing needs.
Radial Tires
Radial trailer tires are designed with a different structure—the cords inside the tire are arranged at 90 degrees to the direction of travel, which reduces friction and heat buildup. This design offers several benefits:
- Better tread wear: Radials distribute the weight of your trailer more evenly, leading to longer-lasting tires.
- Smoother ride: Because radial tires flex more than bias ply tires, radials give you a smoother ride, making them perfect for highway speeds and long-distance towing.
- Heat resistance: Their design helps them handle higher speeds without overheating, reducing the chance of blowouts during long trips.
Bias Ply Tires
Bias ply tires, on the other hand, have cords that crisscross each other at a 45-degree angle, making them tougher and more resistant to damage from rugged terrain. They shine in a few specific areas:
- Greater strength: Bias ply tires are great for handling heavy loads and rough terrain, making them ideal for off-road adventures or hauling trailers in construction or farm settings.
- Less ideal for highways: However, at highway speeds, they tend to wear down faster and offer a less comfortable ride. The increased friction also generates more heat, which can reduce their lifespan on long highway drives.
Maintaining Trailer Tires for Longevity
Trailer tire maintenance is straightforward, but don’t let the simplicity fool you—taking a few minutes for a visual inspection and checking air pressure before each trip can save you from hours of wasted time and hundreds of dollars in repair costs. For a complete guide to maintaining your entire RV, check out our RV Maintenance Checklist.
Proper Inflation and Tire Pressure
Maintaining the proper air pressure in your trailer tires is one of the most critical things you can do as an RV owner. Underinflated tires increase friction, which leads to heat buildup and, eventually, blowouts or other serious tire problems.
Before each trip, we always make it a habit to check the air pressure in our tires. It only takes a few minutes, but it gives us peace of mind for the miles ahead. If the weather stays consistent, our tire pressure holds steady all summer. But as soon as fall rolls around and temperatures drop, we notice the pressure starts to dip.
That’s where our trusty Viair compressor comes in! It quickly brings our ST tires back to the manufacturer’s recommended levels, ensuring we’re road-ready. It’s a small step that makes a big difference in avoiding costly blowouts and keeping your tires in top shape.
Keeping your tire pressure within the manufacturer’s recommended range is key to extending the life of both ST and LT tires. Underinflation can cause uneven wear, reduce your tires’ load capacity, and put your entire trip at risk. So, make sure to check your tire pressure regularly—it’s one of the simplest but most effective maintenance steps you can take!
Inspect for Flat Spots and Wear
Flat spots and wear can sneak up on you, especially if your trailer has been sitting idle for a while. Typically, if a trailer has been stationary for 30 days or more, the tires can start to develop flat spots, particularly when parked on hard surfaces like concrete or asphalt.
It’s not just flat spots you need to watch out for—always inspect the sidewall of the tire for cracks or signs of dry rot. Dry rot occurs when tires are exposed to the elements over time, especially in hot, dry climates, weakening the rubber and making the tires more prone to failure, even if they still have plenty of tread.
If your trailer has been sitting for several months, or if the tires have been carrying weight without moving, it’s essential to check for flat spots. These can affect the balance of the trailer, lead to uneven wear, and eventually cause tire problems on the road.
To avoid these issues, consider moving your trailer periodically or using tire covers and blocks to protect the tires from the elements and relieve pressure. Regular inspections of both the tread and sidewalls can save you from major headaches. If you notice dry rot or damage, it’s best to replace the tire before it becomes a safety issue during your next trip. Catching these problems early can save you time, money, and a whole lot of stress!
When to Replace Trailer Tires
Knowing when to replace your trailer tires can save you from unexpected blowouts or worse—being stranded on the side of the road. Tires may look fine at first glance, but there are some telltale signs that mean it’s time for a change.
Signs of Wear and Damage
Trailer tires are constantly exposed to the elements, heavy loads, and long trips, so they wear down over time. Here’s what to look for when deciding if it’s time to replace them:
- Cracks and Dry Rot: Inspect the sidewall of the tire for any cracks or signs of dry rot. This is especially common if your trailer has been parked for extended periods. Dry rot weakens the rubber, even if the tread looks fine, and can lead to tire failure.
- Tread Separation: Check for tread separation, which happens when the layers of the tire start to come apart. This is a serious safety issue and should not be ignored. If you spot it, it’s time to replace your tires immediately.
- Frequent Blowouts: If you’re experiencing frequent blowouts or other tire problems, it’s a clear sign that your tires are worn out or not suited for your load. Even if the tire looks fine, repeated blowouts indicate that the tire’s structure has been compromised.
- Uneven Wear: Look for uneven tread wear, which could mean the tires are out of balance or improperly inflated. This can reduce your tires’ lifespan and lead to blowouts on the road.
Trailer tires should typically be replaced every 3 to 6 years, even if they haven’t hit their mileage limit. Rubber deteriorates over time, so even tires that aren’t in use can become unsafe. Regular inspections can help you avoid costly damage and ensure that your next trip goes off without a hitch.
Frequently Asked Questions about Trailer Tires
Here are the FAQs with answers you can include in your article:
1. What are safe tread depth levels for trailer tires?
Safe tread depth for trailer tires is typically at least 2/32 of an inch. You can use a penny test to measure this – insert a penny into the tread with Lincoln’s head facing down. If you can see the top of Lincoln’s head, your tread is too low, and it’s time to replace the tire. For optimal performance, it’s best to replace tires when the tread depth reaches 4/32 of an inch, especially if you frequently tow heavy loads.
2. Can you plug a trailer tire?
Yes, you can plug a trailer tire as a temporary fix if the puncture is small and located in the tread area. However, plugging isn’t recommended for long-term use, especially for trailer tires that carry heavy loads. For the best safety and performance, it’s advised to replace the tire or have it professionally patched and repaired from the inside at a tire shop. Always avoid plugging tires with damage on the sidewalls.
3. What equipment do I need to change an RV Trailer Tire?
We recommend the following equipment to change a trailer tire:
- Spare Tire
- Portable air compressor (like a Viair)
- Bottle Jack and Jack Stands
- Breaker bar and Impact wrench
- Torque Wrench
- Safety cones and vest
Conclusion: Trailer Tires vs Car Tires – Why the Right Choice Matters
When it comes to trailer tires vs car tires, choosing the right tire is crucial for safety, performance, and longevity. Trailer tires (ST tires) are specifically designed for the unique demands of towing heavy loads, while car tires (P or LT tires) fall short when handling the extra weight and stress of trailers, RVs, and fifth wheels. By sticking to ST tires, you’ll reduce the risk of blowouts, improve handling, and extend the life of your tires. Regular inspections, proper maintenance, and using the right tire for your specific needs will keep your trailer rolling smoothly and safely on every adventure.
About Us
We are Mike and Sara, and our kids and dog are exploring the US while camping in our fifth wheel! Since the late 90s we have been exploring the great outdoors one hiking trail at a time. We introduced our kids to hiking while they were young and they love exploring new places. We call Kentucky home and we find ourselves exploring the state parks, national parks, and other wildlands in our area as often as we can!
Our RV camping journey began during the COVID-19 pandemic. Waking up close to the trails we love hiking was enough for us to get hooked on the camping lifestyle! Thanks for following our adventures!
