SeattleLion
Well-known member
I think I am pretty typical. We bought our first RV a TT last June. In February we sold it and bought a Bighorn. So we are fairly new to all of this RV stuff. Reading the dire posts about the Tow Max tires caused me considerable anxiety until I started thinking about it. While I am new to RV's, I am not new to tire issues. Over the last few years I have done performance (on the race track) driving. To do that safely, you need to understand a lot about tires and tire performance. Consistent driving over 100 MPH puts special demands on a car and its tires.
I learned about loading, heating, etc. This is very relevant here. First of all there is no real evidence that the Tow Max tires are any better or worse than any other load range E tire. There seems to be a strong feeling that Chinese products are inferior. This further fed the idea that the OEM tires are dangerous. Since I don't want to ignite further debate, for this post let's leave it with the fact that we just don't know if the Tow Max tire is better or worse than any other ST LR E out there. (There aren't many)
If we start with that premise, I think we can get to the root cause of all this tire concern. I really think the problem is that Load Range E tires are too close in capacity to many of our trailers. As far as I can tell, the Tow Max LR E tires have a static load rating at about 3,000 lbs. That gives them a 12,000 lb total load capacity for the two axles. My 3160 is about 12,000 lbs dry. 2,100 lbs go to the hitch, leaving 9,100 lbs on the wheels. Add 1,500 lbs of load and the wheels are carrying about 10,000 lbs. This is about 85% of capacity. Now it is very unlikely that my load will be evenly balanced across the trailer, so one side will be carrying more than 5,000 lbs. So there is a risk of pushing the tires on one side closer to capacity.
In defense of Heartland, a 15% margin on the tire loading isn't really bad. It's acceptable engineering. However, it is a smaller margin than I want. On the race track I wouldn't drive on tires that were rated for 125 mph max speed even though my top speed was only 110. We all know that the closer we get to a limit on a mechanical system, the more likely a component will fail. This brings us back to the original point, the overall failure rate of Tow Max across all RV's wearing them is probably acceptably low. However, those of us with heavy fifth wheels have a higher risk of failure because of the smaller margin of loading. How big this increased risk actually is, we don't know. The anecdotal evidence here is no help.
There is one other factor that dramatically reduces a tire's load capacity: inflation pressure. If a tire is inflated to less than the correct amount, the load carrying capacity is going to go down. Since we were at 85% capacity at full inflation, a small reduction in pressure will overload the tire. This is what I think causes the most failures. Does that mean that by maintaining proper inflation pressure we can reduce our risk of tire failure? I think it does. Does it mean that we will never have a tire fail? Nope.
Again the issue is percent of rated capacity. The reason my car and truck tires don't fail is largely because I am operating well below rated capacity. All of my vehicle tires are running at 75% or less of rated capacity. That margin really pushes down the likelihood of tire failure. I think it stands to reason that if I can do the same thing with the trailer, I can similarly reduce my risk.
I think this is why we have so many happy campers after they buy load range G tires. They have increased the load rating of the tires to around 4,000 lbs each. The two axles now have a 16,000 lb capacity. This will provide the desired 25%+ margin.
The reason I am writing all of this is to try to help keep things in perspective. Basically, if I stay with the OEM Tow Max tires for a year or so, and I keep them at 80PSI, I can expect a relatively small chance of a failure. If I want to push that probability down further, I can spend about $1,400 for a set of Goodyear LR G tires.
I think the above is an accurate picture of what is really going on. Those of us who are financially stressed buying a new luxury trailer don't have to be emotionally pressured into thinking we need to scrape up even more money to replace brand new tires. It seems to me that before making that additional expenditure, we should weigh the facts versus the emotional pain that people who did have a failure experienced. If we can afford to further reduce the risk, fine. But if we can't, we are not putting our families and our new property in serious jeopardy.
I learned about loading, heating, etc. This is very relevant here. First of all there is no real evidence that the Tow Max tires are any better or worse than any other load range E tire. There seems to be a strong feeling that Chinese products are inferior. This further fed the idea that the OEM tires are dangerous. Since I don't want to ignite further debate, for this post let's leave it with the fact that we just don't know if the Tow Max tire is better or worse than any other ST LR E out there. (There aren't many)
If we start with that premise, I think we can get to the root cause of all this tire concern. I really think the problem is that Load Range E tires are too close in capacity to many of our trailers. As far as I can tell, the Tow Max LR E tires have a static load rating at about 3,000 lbs. That gives them a 12,000 lb total load capacity for the two axles. My 3160 is about 12,000 lbs dry. 2,100 lbs go to the hitch, leaving 9,100 lbs on the wheels. Add 1,500 lbs of load and the wheels are carrying about 10,000 lbs. This is about 85% of capacity. Now it is very unlikely that my load will be evenly balanced across the trailer, so one side will be carrying more than 5,000 lbs. So there is a risk of pushing the tires on one side closer to capacity.
In defense of Heartland, a 15% margin on the tire loading isn't really bad. It's acceptable engineering. However, it is a smaller margin than I want. On the race track I wouldn't drive on tires that were rated for 125 mph max speed even though my top speed was only 110. We all know that the closer we get to a limit on a mechanical system, the more likely a component will fail. This brings us back to the original point, the overall failure rate of Tow Max across all RV's wearing them is probably acceptably low. However, those of us with heavy fifth wheels have a higher risk of failure because of the smaller margin of loading. How big this increased risk actually is, we don't know. The anecdotal evidence here is no help.
There is one other factor that dramatically reduces a tire's load capacity: inflation pressure. If a tire is inflated to less than the correct amount, the load carrying capacity is going to go down. Since we were at 85% capacity at full inflation, a small reduction in pressure will overload the tire. This is what I think causes the most failures. Does that mean that by maintaining proper inflation pressure we can reduce our risk of tire failure? I think it does. Does it mean that we will never have a tire fail? Nope.
Again the issue is percent of rated capacity. The reason my car and truck tires don't fail is largely because I am operating well below rated capacity. All of my vehicle tires are running at 75% or less of rated capacity. That margin really pushes down the likelihood of tire failure. I think it stands to reason that if I can do the same thing with the trailer, I can similarly reduce my risk.
I think this is why we have so many happy campers after they buy load range G tires. They have increased the load rating of the tires to around 4,000 lbs each. The two axles now have a 16,000 lb capacity. This will provide the desired 25%+ margin.
The reason I am writing all of this is to try to help keep things in perspective. Basically, if I stay with the OEM Tow Max tires for a year or so, and I keep them at 80PSI, I can expect a relatively small chance of a failure. If I want to push that probability down further, I can spend about $1,400 for a set of Goodyear LR G tires.
I think the above is an accurate picture of what is really going on. Those of us who are financially stressed buying a new luxury trailer don't have to be emotionally pressured into thinking we need to scrape up even more money to replace brand new tires. It seems to me that before making that additional expenditure, we should weigh the facts versus the emotional pain that people who did have a failure experienced. If we can afford to further reduce the risk, fine. But if we can't, we are not putting our families and our new property in serious jeopardy.
