Community Forums

danford50 · 02-03-2019, 12:51 PM

help me to understand, I weight my coach and the steer axle tires had a weigh of 4320, do I take that number(4320) divide it by 2 and then look for that number(2160) on the tire chart and that is the weight for my steer axle tires?

FlyingDiver · 02-03-2019, 01:30 PM

That's basically it. But to do it right, you need individual wheel (position) weights. If all you have is axle weights, then you'll need to go up at least one weight bracket. Probably two. Because you can't assume the coach is balanced left to right.

TJ · 02-03-2019, 01:57 PM

Quote:

Originally Posted by danford50

help me to understand, I weight my coach and the steer axle tires had a weigh of 4320, do I take that number(4320) divide it by 2 and then look for that number(2160) on the tire chart and that is the weight for my steer axle tires?

If all you have is the axle weight, I recommend using 55% of the total for each side. Rarely do opposing sides of an axle weigh the same. Using the 55% "fudge factor" provides you a little cushion to cover a possible variance. In your case, 4320 x .55 = 2,378.75 for each corner. Round up to 2,380 for ease of calculation.

Obviously, getting an actual corner weight is the best solution. I have success using state weigh stations that are temporarily closed to do this. They usually leave the scales (and displays) active so truckers can do a self-check. I'm lucky enough to have one about 20 miles away and it is frequently not staffed.

In either case, when you consult the tire manufacturer's tables, be sure you are using the proper one for your tire size. And, if your actual weight falls between two chart weights (as it likely will), round UP to the next chart weight. I also like to add a 5-10 psi cushion, but that's just me.

TJ

danford50 · 02-03-2019, 04:05 PM

Quote:

Originally Posted by Tranquil Jim

If all you have is the axle weight, I recommend using 55% of the total for each side. Rarely do opposing sides of an axle weigh the same. Using the 55% "fudge factor" provides you a little cushion to cover a possible variance. In your case, 4320 x .55 = 2,378.75 for each corner. Round up to 2,380 for ease of calculation.

Obviously, getting an actual corner weight is the best solution. I have success using state weigh stations that are temporarily closed to do this. They usually leave the scales (and displays) active so truckers can do a self-check. I'm lucky enough to have one about 20 miles away and it is frequently not staffed.

In either case, when you consult the tire manufacturer's tables, be sure you are using the proper one for your tire size. And, if your actual weight falls between two chart weights (as it likely will), round UP to the next chart weight. I also like to add a 5-10 psi cushion, but that's just me.

TJ

Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel

"007" · 02-03-2019, 04:11 PM

You will find tire pressures explained here.

FlyingDiver · 02-03-2019, 04:14 PM

Quote:

Originally Posted by danford50

Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel

Same as for singles except there should be separate lines on your tire inflation chart for duals.

Norm Mac · 02-03-2019, 04:31 PM

You have been given some great advice here but I would like to take you in a different direction...
I would be suspicious of the weights you have received.
You did not specify what coach you have but the axle weights seem very low to me.
Even if you have Newmar's lightest coach, a 27' BayStar Sport, the weights you list are still low, if you have a larger coach the numbers are even further off.
According to Newmar, the Unloaded weight of a BayStar Sport 2702 should be approximately 15190.
Your total axle weights (4320 plus 7920) equals 12240.
This is almost 3000 pounds less than the lightest coach Newmar makes when leaving the factory.
I would recommend getting another CatScale weight for this coach unless there is some other factor that I am not aware of.

FlyingDiver · 02-03-2019, 04:33 PM

Quote:

Originally Posted by Norm Mac

You have been given some great advice here but I would like to take you in a different direction...
I would be suspicious of the weights you have received.
You did not specify what coach you have but the axle weights seem very low to me.

I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.

TJ · 02-03-2019, 04:42 PM

Quote:

Originally Posted by FlyingDiver

I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.

Because Newmar owners are such good folks?

TJ

TJ · 02-03-2019, 04:49 PM

Quote:

Originally Posted by danford50

Tj The drive axle weight is 7920 on the rear how would I do it for the dual wheel

Divide by 2, then apply the .55 factor. Use the "dual" numbers shown in the chart.

TJ

Winemaker2 · 02-03-2019, 04:52 PM

Careful...
Different Tire Mfg charts are set up differently - make sure you use the correct one for your tire mfg

Goodyear - uses Load / tire w/ separate lines for single & dual application

Michelin - uses load / axle end w separate lines for single & dual application

Its a subtle difference but you need to use the charts correctly

TJ · 02-03-2019, 06:02 PM

Quote:

Originally Posted by Winemaker2

Careful...
Different Tire Mfg charts are set up differently - make sure you use the correct one for your tire mfg

Goodyear - uses Load / tire w/ separate lines for single & dual application

Michelin - uses load / axle end w separate lines for single & dual application

Its a subtle difference but you need to use the charts correctly

Good point, though I'm thinking that the difference is pretty obvious. With one, the load capacity for single and dual is in the same relative ballpark; with the other, the dual rating is close to double the single. Still, I suppose someone unfamiliar with big tires could get confused.

TJ

Norm Mac · 02-04-2019, 05:18 AM

Quote:

Originally Posted by FlyingDiver

I have no idea why he's posting in this forum. His profile says he has a 30' Thor Freedom Elite, which is a smallish Class C. So those numbers are appropriate.

Now that makes sense,
I see the discussion has been moved out of the Newmar Forum.

veraken · 02-04-2019, 05:32 AM

To determine what the right tire pressure is for you, you need to weigh your MH. Load your MH as you would for travel, fill your gas and water tanks and then get your MH weighed.

If you can't do 4 corner weighing (which would e the best way), this is the procedure to follow:

1. Weigh the coach axles
2. Add 5% to account for possible uneven weight side to side.
3. Divide by the number of tires on each axle.
4. Look to tire chart for your brand to find tire pressure.
5. Add 5 psi for safety