Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

KathyandDave · 10-04-2008, 07:15 AM

This turned out to be lengthy, so grab a coffee...
I'm trying to figure out the optimal inflation pressures for the TV and the trailer. We know that we are not at the maximum rating for the duallies. It's a challenge! So, after much searching...Eureka, I've got it!

For the TV, we have General Ameritrac tires LT215/85R16E. The General website gives no info, except maximums. The plaque on the TV door says that, for the rear axle, the maximum cold pressure is 65lbs., the rated maximum load is 3720kg (8200lbs). Our weighed rear axle with trailer = 3300kg (weighed on an Ontario MTO scale when the officers were not present) = 7273lbs, so each of four tires of duallies = 1818lbs. In the Goodyear http://www.goodyear.com/truck/pdf/pr...Brochure_P.pdf, we find the line for the Goodyear equivalent of our tires and we see that the recommended inflation pressure is between 50 and 55 lbs. A similar exercise for the trailer tires and the TV front tires.

To inflate to the maximum would mean that we are over-inflated, resulting in many deficiencies, including poor traction.

Can I safely transfer Goodyear data to General tires? I think my next tires will be Goodyear or other manufacturer who offers good engineering info!

Places to look at tire info: Tirerack.com (many clear articles), Wikipedia (shows entire load index table and lots more), carbibles.com/tyre_bible.html

One thing that the tyre bible guy emphasizes and other material (including MOC tire guide) hints at is that you MUST replace your tires every five or six years, no matter what, because the rubber compound deteriorates with time, not with usage. When buying a tire, look at its DOT manufacture date number. Some tire shops keep stock on the shelf until it sells, so you may be buying a tire that is already past its stale date!

Cold pressure is measured at 65 degrees F. Offset +1 PSI per 10 degrees colder. There's a rule of thumb for temperate climates to offset -2 PSI for reading in the afternoon, -4 for recent driving, -6 for recent long-haul driving. Do this agree with what the Pressure Pro and other units show?

10-04-2008, 07:15 AM	#41
KathyandDave Montana Master Join Date: Aug 2008 Location: Shelburne Posts: 688 M.O.C. #8693	This turned out to be lengthy, so grab a coffee... I'm trying to figure out the optimal inflation pressures for the TV and the trailer. We know that we are not at the maximum rating for the duallies. It's a challenge! So, after much searching...Eureka, I've got it! For the TV, we have General Ameritrac tires LT215/85R16E. The General website gives no info, except maximums. The plaque on the TV door says that, for the rear axle, the maximum cold pressure is 65lbs., the rated maximum load is 3720kg (8200lbs). Our weighed rear axle with trailer = 3300kg (weighed on an Ontario MTO scale when the officers were not present) = 7273lbs, so each of four tires of duallies = 1818lbs. In the Goodyear http://www.goodyear.com/truck/pdf/pr...Brochure_P.pdf, we find the line for the Goodyear equivalent of our tires and we see that the recommended inflation pressure is between 50 and 55 lbs. A similar exercise for the trailer tires and the TV front tires. To inflate to the maximum would mean that we are over-inflated, resulting in many deficiencies, including poor traction. Can I safely transfer Goodyear data to General tires? I think my next tires will be Goodyear or other manufacturer who offers good engineering info! Places to look at tire info: Tirerack.com (many clear articles), Wikipedia (shows entire load index table and lots more), carbibles.com/tyre_bible.html One thing that the tyre bible guy emphasizes and other material (including MOC tire guide) hints at is that you MUST replace your tires every five or six years, no matter what, because the rubber compound deteriorates with time, not with usage. When buying a tire, look at its DOT manufacture date number. Some tire shops keep stock on the shelf until it sells, so you may be buying a tire that is already past its stale date! Cold pressure is measured at 65 degrees F. Offset +1 PSI per 10 degrees colder. There's a rule of thumb for temperate climates to offset -2 PSI for reading in the afternoon, -4 for recent driving, -6 for recent long-haul driving. Do this agree with what the Pressure Pro and other units show?