BAC Forum
General Boards => Technical Support => Topic started by: Lawrence Tarnoff on July 23, 2020, 03:03:38 AM
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Anyone have an inflation chart for Hankook A37? Google has let me down.
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I didn’t find one for the A37 specifically but it list the inflation for Hankook tires by size and load rating. Hope this helps.
https://rvsafety.com/tools/tire-inflation-tables
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Thanks, Chuck. That works!
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So what pressures did you end up running?
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I have steer and drive axle weights. Steer axle is 11020 lbs. So that gives me 5,510 per side or 100 psi per tire. Drive axle is 18640 or 9,320 per side or 95 psi per tire. I just bought new drive tires at Pomps and provided them with the weights. They said I should run 105 all around. I think I'm going to go with the chart, but would be interested in hearing other opinions.
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It’s not uncommon to add a safety margin to the suggested inflation numbers. I do this also by 10%. I’d rather be a little high than a little low.
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Lawrence,
On most Beaver coaches, especially in the SMC era of production, the axle weight is not evenly divided between the right and left tires on the axle. I have seen over a thousand pounds difference between the right and left tires on the same axle. So since you are taking the axle weight and dividing it in half to get your tire loading, you are very probably overloading one or two of your wheel locations by using the minimum allowed pressure on the chart. That is the reason that all RV tire safety sources recommend weighting each wheel location instead of each axle location. However, that being said, since you have a 2003 Monterey that probably has a rear radiator and a front mounted generator, I would not expect more than 2 to 400 lbs. difference from one side to the other.
Gerald
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Why not just run at maximum inflation? I find it hard to believe there would be a discernible difference in ride quality between 110 and 120 psi. Is there another reason?
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Why not just run at maximum inflation? I find it hard to believe there would be a discernible difference in ride quality between 110 and 120 psi. Is there another reason?
While you would be safe at the maximum psi, there can be handling issues. If the tire is not flexing enough it may ride harsher and follow the grooves in the road making for an unpleasant ride. Not to mention hitting the expansion joints with more of a jolt. Just my opinion on it, but proper inflation for the load does seem to give the best ride.
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Why not just run at maximum inflation? I find it hard to believe there would be a discernible difference in ride quality between 110 and 120 psi. Is there another reason?
It made a huge difference on mine! You can see in some of my early, 2014, posts complaining about harsh ride, following the crown of the road and following grooves in the road. Once I set the proper pressures on my tires, especially the tag, everything smoothed out nicely. Amazing how much difference 5-10 PSI made. More like 20 for the tag. Just my 2 cents!
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Excellent resource for all things round and rubber:
https://www.rvtiresafety.net/
Fmr tire engineer and (now) motorhome owner
Remember, Max pressure listed on the tire sidewall is actually the MINIMUM pressure required to support the maximum WEIGHT listed on the tire sidewall. Semantics, I know.........
I also know that on our 15+ ton motorhome, I can't tell the difference in ride that +- 10 psi in front tires make. I run 120 psi in the fronts. That includes a +10% safety factor. 295-80-22.5 tires.
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I agree with Bill, in that lowering the pressure on my drivers and tag to the minimum allowed in the table (315/80/22.5) made no discernable difference in ride or handling on my coach, so I run 130 PSI all of the way around. My front axle had virtually no room to lower from the max cold inflation on my tires of 130 PSI, since I am just north of 17,000 lbs. on my front axle when loaded with full tanks.
Gerald