I recently received this question from an RVtravel.com reader regarding using larger tires with lower inflation to get a more comfortable ride while maintaining safety and not overheating the tires.
Hi Roger,
I have a tire question for you. I own a 2021 RV with a GVWR of 8596 lbs. that I purchased used in the spring of 2024. The factory 205/75R15 Goodyear Endurance tires were manufactured in November 2019, and I believe they are due to be replaced. I am considering replacing them with GY Endurance 225/75R15 for the increased load range to give myself a wider margin of safety, as the 205s’ load range is basically equal with the GVWR for the camper.
The question
My 205s are rated for 2150 lbs. at 65 psi, which is what I’ve been running them at. According to the Load/Inflation chart, I could theoretically run the 225s at 50 psi for the same 2150 load. Obviously, I want more load capability so I would run them at a higher psi, say 55 or 60. But is it safe to run them at a lower psi since they are rated to 2830 lbs. at 80 psi? I don’t need that much load capability and would prefer the softer ride of a lower pressure as long as it’s safe to do so and not be overheating the tires.
Please let me know what you think with regards to running this particular tire at less than max psi. —Jeff D.
My reply
Hi Jeff,
First, it’s essential to understand what the “GVWR of 8596 lbs.” means. The Gross Vehicle Weight Rating (GVWR) is the heaviest your RV should ever be. In fact, the RV Industry Association (RVIA) recommends that the tire loading should be no more than 90% of that number. Additionally, certain assumptions are made when arriving at that number, namely, that the load on your tires is evenly split between the axles and that the load on each tire on an axle is evenly distributed from end to end.
RVSEF (RV Safety & Education Foundation) has measured the actual load on tires on tens of thousands of RVs and learned that more than half of the tires in RV usage are being overloaded. This data supports the recommendation that, at a minimum, every RV should get on a truck scale and at least learn the weight on each axle. Getting “4-Corner Weights” is not always convenient (see RVSEF), so I suggest we assume one end is supporting 53% of the axle total. Going to this effort is important as the inflation in the tables is the MINIMUM inflation for the heaviest loaded individual tire, and all tires on the trailer should have the same cold inflation.
You mention “safety” a few times. Tire inflation safety is not an on/off switch where tires will quickly fail if you drop 1 psi below the table number or run for 10 years if you are a few psi above the minimum.
If you review my posts on my blog RVTireSafety.net, or if you do a search on “Tire Inflation” on the RVtravel.com Maintenance tab you can find many posts on the topic.
The short answer to the question on new tires
Yes, you can go up in load capacity IF you also go up in inflation and up in Load Range.
I recommend you confirm the load on each axle when the RV is fully loaded to the heaviest you ever expect to be (full water, food, tools, clothes, people, etc.) by getting on a truck scale.
Use the scale reading from the heavier axle and apply the suggested 53% figure to arrive at your tire loading number.
Consult the Load & Inflation tables for your size and Load Range tire to learn the MINIMUM cold inflation that you would use for all four tires.
On my RV, I use the above and then add 5 psi to that number and make sure my inflation never drops below the Minimum by reading my TPMS display.
I hope this isn’t too much info.
Roger Marble
MORE POSTS FROM ROGER ON TIRE PRESSURE
- My RV tire pressure is showing a significant increase. Is this OK?
- Is the tire pressure too high?
- Should you adjust tire pressure when temps get colder?
- Do not adjust your tire pressure for ambient temperature
- Understanding what temperature change does to tire pressure
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Thank you for your answer and explanation, Roger. Have a great week and safe travels!
I thought load was based on more than just tire capacity. You also have to take into account, wheel bearing capacity, braking capacity, suspension capacity and axle capacity. I would think that upgrading tires to a higher load range could put these other capacities at risk. Or am I wrong in this assumption?
The original question was about “Up-rating” the tires for an increased “Safety Margin”. I did not interpret the question as being about increasing the load capacity of the RV. Yes the other components of the suspension have load limits which should not be exceeded. I do not see how increasing the “capacity” of the tires would increase the load on the RV suspension components. Jeff was looking for increased safety margin of the tires.
You must also consider clearance between the tires and the wheel well. Maybe bump up by 10 mm steps with each tire purchase every few years? And don’t forget to compare GPS speed versus dashboard speed as it depends on outside diameter.