Tire Pressure determined by Axle weight

[jgallego]

I want to make sure I am understanding how to calculate your tire pressure based on you axle weight.  I went to the Love's Cat scale today and weight my 2018 Pace Arrow 36U.  The front axle was 9,220 and the rear axle was 17,160 pounds. On the motor home placard it says to put 120 pounds in each tire.  Below is the chart from Michelin for the tires I have on my motor home.  So do I divide the front axle weight by 2 to get the pressure for the two wheels on the front.  In this case it would be 4,610 pounds.  On the chart below it would be at 95 pounds.  The rear axle weight is 17,160 so divided by two would be 8,580 per end.  So it would be around 95 pounds for each of the 4 rear tires.  Is this correct.

My gvwr is 29,500  and the gvcr is 33,000 pounds.  My front axle rating is 10,500 pounds and the rear axle rating is 19,000 pounds.

Thanks I want to make sure I do it correctly.  There is not really a lot of explanation on the web site.

 

255/70R22.5 H XZE®
PSI		80	85	90	95	100	105	110	115	120	Maximum load & pressure on sidewall
kPa		550	590	620	660	690	720	760	790	830
LBS	Single	4190	4370	4550	4675	4895	5065	5205	5400	5510	S	5510 LBS at 120 PSI
	Dual	7940	8220	8550	8820	8910	9220	9350	9830	10140	D	5070 LBS at 120 PSI
KG	Single	1900	1980	2060	2120	2220	2300	2360	2450	2500	S	2500 KG at 830 kPa
	Dual	3600	3720	3880	4000	4040	4180	4240	4460	4600	D	2300 KG at 830 kPa

[richard5933]

You don't have a four corner weight, so you'll be somewhat guessing. Based on Roger's advice in this type of situation use 53% of the total axle weight as the weight of each end (assuming that one end is going to be heavier than the other).

http://www.rvtiresafety.net/2018/11/setting-tire-pressures-on-cold-days.html

Use that number to calculate the minimum pressure. Then, add a 10% buffer to the minimum pressure to obtain the cold inflation pressure you're going to use.

In your case, that would be 9220 x .53 = 4887 for each of the front wheels. The Michelin chart shows a minimum pressure of 100 psi, and with the extra 10% that makes 110 psi for cold inflation pressure.

The rear axle would be 17,160 x .53 = 9095 for each axle end. The chart shows 105 psi, and with the extra 10% you've got about 115 psi as cold inflation pressure for the rears.

It's late though, so please double check the math before using these numbers.

[jgallego]

Your numbers are correct.  I read Roger's article on setting the motorhome tire inflation and it makes sense.

Thanks for the information.

 

[rayin]

On 5/13/2019 at 9:00 PM, richard5933 said:

You don't have a four corner weight, so you'll be somewhat guessing. Based on Roger's advice in this type of situation use 53% of the total axle weight as the weight of each end (assuming that one end is going to be heavier than the other).

http://www.rvtiresafety.net/2018/11/setting-tire-pressures-on-cold-days.html

Use that number to calculate the minimum pressure. Then, add a 10% buffer to the minimum pressure to obtain the cold inflation pressure you're going to use.

In your case, that would be 9220 x .53 = 4887 for each of the front wheels. The Michelin chart shows a minimum pressure of 100 psi, and with the extra 10% that makes 110 psi for cold inflation pressure.

The rear axle would be 17,160 x .53 = 9095 for each axle end. The chart shows 105 psi, and with the extra 10% you've got about 115 psi as cold inflation pressure for the rears.

It's late though, so please double check the math before using these numbers.

Reads right to me.

 

 

[tireman9]

richard5933  is correct

He gets a Gold star for doing the homework and knowing the correct answer.😄