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Old Harry · 01-05-2022, 08:51 AM

I know the tire load vs. PSI thing has been discussed on several threads but I have a specific question.
I have Hankook Smart Flex AH35 brand on my coach. Size is 265/70R 19.5 and listed loads on the sidewalls are:

Single 5070 lbs @ 110 psi
Dual 4675 lbs @ 110 psi

I have had the coach weighed on the two axles. This was the loaded weight while on our recent trip and with full fuel, 75% water and empty gray and black tanks and both my better half and me aboard.

Using the thumbnail formula, "How to get tire weight using Cat Scale" I found here to figure possible weight on each tire. But it uses Toyo tire charts as an example. My numbers came out to be:

The steer tires come to 4,368 lbs each tire and the duals came to 3,501.75 on each tire.

What I cannot find is a chart for the Hankook Smart Flex AH35 tire. I can find passenger Hankook tires load/psi charts and I can find the Smart Flex tires for sale but no luck finding the load/psi for this tire.

Should I use some other tire manufacturers chart, like Toyo? Or does someone know where to find the Hankook chart for this tire?

richard5933 · 01-05-2022, 09:11 AM

The information you want (Load & Inflation Tables) is located in the back of this publication:

https://www.hankooktire.com/us/files...og_0821_01.pdf

It's a large download, but if you have the tires you'll want a copy.

D Gardiner · 01-05-2022, 09:12 AM

Here is another chart:

https://www.rvsafety.com/images/pdf/...ntable2019.pdf

Old Harry · 01-05-2022, 03:07 PM

Thank you. That is exactly what I was looking for.

richard5933 · 01-05-2022, 03:31 PM

Every manufacturer (other than a couple of the no-name import brands) publishes a tire data book for their tires every year. Not only is it a great catalogue of the different tires they're selling, it contains lot of information about load & inflation, acceptable rim & wheel sizes, and more. Always nice to get a copy from the dealer when you buy your tires. They usually have a few behind the counter somewhere.

FlyboyTR · 01-05-2022, 06:24 PM

There is a mathematical formula that you can also use in the absence of the proper tire inflation chart. This is old school stuff but can get you really close. However, it is always best to add 5-7 lbs over what the formula give you. This provides a safety factor for additional weight you may add, tire loading in a turn, etc.

The following is taken from the data you provided.
Single 5070 lbs @ 110 psi
Per wheel weight (front) 4,368 lbs

Here's the formula. You divide the max air pressure listed on the tire into the max weight capacity for the tire. 5070 / 110 = 46.09. That tells you that each pound/PSI of air pressure will support 46.09 pounds of weight. Now divide the actual wheel weight by the 46.09: 4368 / 46.09 = 94.77. That 94.77 is the PSI needed for the tire to carry the stated weight. Based on that, I would be running that tire at 100 lbs, cold inflation. that would give me a little extra carrying capacity.

That said... using an inflation chart is best...but knowing how to figure the PSI needed (as a base) without a chart can save you a lot of grief.