Thread Tools Search this Thread Display Modes
Old 04-25-2003, 03:00 PM   #1
2 Rivet Member
1978 25' Tradewind
Roseland , Florida
Join Date: Aug 2002
Posts: 52
Images: 1
Tire pressure & towing

Hi everyone,
What is the consensus for tire pressure on the mh when you are towing a car? I have a 345 with 8R 19.5's & tow a saturn wagon. The tires are embossed with a max cold of 110 PSI, but the manual says 70 front, 60 duals, & 60 tag. The PO said 81 all around. That's 3 opinions, any more out there??
Eric, currently So Fla, but outta here soon.

kooblekidz is offline   Reply With Quote
Old 04-26-2003, 12:22 PM   #2
3 Rivet Member
Join Date: Apr 2003
Posts: 119
Here is a copy of a post I submitted in reply to a prevous tire pressure question. I do not know how to reference older posts yet in this system so I just copied it. A considerable discussion followed this post. Maybe the moderator will inform you on how to get to the original post.
I worked for Michelin Tire Corporation for 7 years and Yokohama Tire Corporation for 11 years. I have given numerous tire seminars on tire maintenance and especially how to determine the correct tire pressures. So here goes.
The pressure on the sidewall of the tire is the maximum pressure at the published load at approximately 55 mph. (The speed can vary somewhat but it is not important for our discussion).
The air pressure is required to support the load that the tire must carry in such a manner that the tire flexes at the designed place on the sidewall of the tire.
If the load on the tire changes then the air pressure should change accordingly to keep the tire flexing at the proper place.
The reason for correct air pressure is to prevent the tire from overheating. It was put together with heat and it will come apart the same way. An under inflated tire will eventually self destruct due to excessive heat build up. An over inflated tire will ride harshly and be more likely to burst upon impact. Sorry for the long explanation but here is the bottom line.
To determine the correct air pressure, check the pressure when the tire is cold. Run the tire for several miles at highway speed. Stop and immediately check the air pressue in the tire. It should be higher than when cold but no more than 10% higher.
Now here is the hard to believe part. If the pressure is more than 10% higher you must ADD AIR and test again. For example if you start with 50 psi cold. If the pressure is 60 when hot, you have exceeded the (10%) in this case, 55 psi maximum safe heat build up pressure. You must ADD AIR. In this case I would add 5 psi which would take the tire to 65 psi when hot. After you run the tire again you will find the pressure to actually drop because the tire will run cooler. The heat build up causes the tire pressure to increase when under inflated.
On the other hand, if the 50 psi cold pressure does not change when hot. You have more air than needed. You can remove 5 psi or so and test again when they return to cold. Like the next trip you take.
So a fully loaded rig will require more air in the tires than one with empty tanks and a light load on board. Always error on the side of over inflation. Thus the maximum sidewall pressure indicated on the tire is usually used. It usually is more than needed. Each axle has its own requirement based upon the load on that axle.

AccessMaster is offline   Reply With Quote
Old 04-26-2003, 01:02 PM   #3
Join Date: Feb 2003
Posts: 544
Images: 29
Here it is
femuse is offline   Reply With Quote
Old 04-26-2003, 04:25 PM   #4
Rivet Master
59toaster's Avatar
1959 22' Caravanner
Atlanta , Georgia
Join Date: Feb 2003
Posts: 2,197
Images: 22
Is the car on a trailer or are you flat towing it? If your flat towing it doesn't matter because because none of the vehicles weight would actually be carried by the tow vehicle.

Now if it's on a trailer then your carring about 750lb or so in Tounge weight and yes you need to adjust the tire pressure.

I have been playing with the method Acessmaster outlined and I passed it on to another board. It work's great! The only monkey wrench is outside temperature. It will change the tire pressure a couple PSI from morning (50deg) to late afternoon (70deg). I have been playing with this in the afternoon to keep the temp more of a constant of what it will be like for summer. Others that have tried it where I posted it are reporting the same sucess.
1959 22' Caravanner
1988 R20 454 Suburban.
Atlanta, GA
59toaster is offline   Reply With Quote
Old 04-28-2003, 12:34 PM   #5
3 Rivet Member
Join Date: Apr 2003
Posts: 119
Rember that it is heat that is the enemy of the tire.
When you know what your hot tire pressures should be for your rig, you can then check them anytime. If your are driving under extremely hot conditions and you find your air pressures are higher than normal when you check them hot, you need to add air to prevent the tire from overheating. DO NOT BLEED AIR FROM AT TIRE THAT IS HOT BECAUSE YOU THINK IT IS BUILDING UP TOO MUCH PRESSURE! That will only make the tire run hotter.
Don't forget that tires do loose pressure over time and need to be reinflated.
AccessMaster is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
tire pressure wb13798 General Motorhome Topics 16 01-27-2007 12:31 PM
dual wheel tire pressure jpurdy Tires 2 10-14-2006 11:03 PM
Z71 or Z85? River Rat Tow Vehicles 7 05-09-2003 04:40 PM
Tire Problem? Pressure Question montanaandy Tires 1 04-22-2003 08:56 PM
Tire Pressure TBYRNE Tires 11 08-09-2002 09:04 PM

Featured Campgrounds

Reviews provided by


This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.

All times are GMT -6. The time now is 11:07 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.