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03-12-2020, 08:51 AM #1
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Depending on GVWR, do you run < 80 PSI with E rated tires?
I saw the chart below for Goodyear's tire pressure recommendations for the Goodyear Endurance tires on the "other" Grand Design forum. Some were recommending to follow the chart. I just got the Endurance tires 2 days ago and had always run 80 PSI with the Westlakes. Considering my trailers GVWR of 12,000 lbs and allowing for about 2400 lbs for the pin weight it looks like I should be running about 45 PSI. Since the drivers side of the trailer is heavier due to the kitchen slide with the frig etc I would add some margin and be at about 60 psi.
I'm just not comfortable with this and I'm inclined to just run 80 so the tires will run a little cooler. I also have a rather sharp backing turn (about 70 degrees) to get into my driveway and feel like the tires will scoot better without deforming as much with the higher pressures. For those with the Endurance tires or even the Westlakes do you run less than 80 based on your loaded weights?
Last edited by HighFive; 03-12-2020 at 08:55 AM.
2019 303RLS Reflection 5th Wheel
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03-12-2020, 09:37 AM #2
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I run my 80 PSI max ST235/80R16 LRE Westlakes max load 3520 lbs @65 PSI for our relatively light 303 vs the tire capacities. Yes, we could run less but when fully loaded our street side is about 1000 lbs. (@ roughly 5000lbs) heavier than the curb side @ about 4000 lbs.
For this heavier street side weight and a little buffer this equates to about an 80% factor for 80 PSI max air pressure @ 65 PSI and thus a load of 5600 and change rather than the max rating of 7040 for the two tires. Having a cushion for this weight and the abuse these ST tires can go through, using 65 PSI seems a prudent choice.
I have shared many times over the last few years on the forum that we had a tire industry veteran of 40ish years (@Ricktulsa) address many, many tire issues and questions and this was one of the topics. I encourage folks to read his posts and learn from a highly valued industry veteran. He was (or may still be) a Solitude 384 owner as I recall.
Also, recall why the RV industry and some other tire industry folks recommend using max tire pressure. It is because many RVs are built using tires that have to be at or must be close to the max rated PSI for the RV loads to match the tire maximums. Also many folks do not understand or choose not to learn about tires let alone most other things about their RVs so it best to be safe and run the max PSI. The RVs built with heavier rated tires (and the many of us that have changed out to heavier rated tires) can be run at the proper less PSI to match the load as many charts indicate and industry veterans know.
DanDan & Carol
2014 303RLS Reflection #185 (10/2013 build)
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03-15-2020, 07:12 AM #3
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HighFive you only mention the pro of better fuel economy, but there are several downsides to excess pressure. Like a stiffer ride, a smaller contact patch, which means less traction and longer braking distances. The stiffer sidewalls further reduce the braking ability like a worn set of shocks or struts when the road isn’t smooth. The centers of the tread will also wear quicker. You mention that tight turn into your driveway, that excess pressure is stiffening the sidewalls and forcing that tread to eat all the scrubbing rather than allowing the sidewalls to flex.
Our TV has way more tire capacity than weight and I ended up at 47-50psi when not towing. Even at 60psi the ride gets jittery and overly harsh. I’m a believer in those tables after adjusting my own. I think it’s transmitting more bumps into the trailer. I’d probably set it at 60 and 50-55 myself.
I also saw no difference in mpgs between 80 and 50. I’ve read a few articles over the years that have tested for the same result, once you reach the optimum ride and handling psi it’s usually just a couple psi from the optimum psi for mpg.
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03-16-2020, 09:37 AM #4
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Thanks for the responses. I read more on the subject on this and other forums as well as web searches and have decided I will run about 65 which according to the chart will handle my weight and give me some margin.
I never mentioned fuel economy. It would be negligible at best and was never my motivation. I just wanted to lesson the odds of having a tire failure and know that pressures that are to low cause heat buildup and failures.2019 303RLS Reflection 5th Wheel
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03-21-2020, 03:06 PM #5
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03-21-2020, 10:04 PM #6
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I always run max pressures as stated on the tire. I never follow a load chart. If you don't have a scale than you are guessing. My tires have a max PSI of 80 and that's what I run. Tire sticker in the truck says 80 and that's what I run in that also. Loaded unloaded its all the same. 80 is way softer than 110 PSI tires that some guys swear by.
To me a chart isn't going to do me much good guessing how much my trailer weighs.
I get it that guys worry about tires but then they worry about everything. Oil load cameras you name it. I trusted the tire shop to sell me a good tire for my trailer and I have about 25,000 miles on them so far and they are fine. They are Mastercraft Corsair.
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03-21-2020, 10:21 PM #7
We've had the Endurance tires for a year and a half and have been running with them at 80 PSI. For our last trip the chart said we could do 55, and my husband felt comfortable compromising at 65 PSI. Our tire monitoring system showed temps to be good during the whole trip.
BTW, our weight is about 2200 lbs on each tire.
One of the reasons we bought the Endurance tires (other than the 2 bad Westlakes we had), was the higher speed limit rating on the Endurance tires.
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03-22-2020, 06:27 AM #8
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I am more concerned with the load capacity and speed rating. I can only run a 80 PSI tire but I travel a lot and I need a tire capable of faster than 50 MPH.
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