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

JABURKHOLDER · 10-28-2016, 11:28 AM

I know a lot has been said about G614's. I also know a lot has been said about what air pressure to run in those tires. I switched to 614's this past jul and I am very happy with them.

I want to comment about pressure. With the "china bombs" you HAD to run max psi (80) just to support our heavy Montanas. With the 614's you do not HAVE to run max psi (110). I truly believe that most folks, including myself, are running these tire at a higher pressure than needed thereby creating a harsher ride for the RV. Things get bounced around enough without adding to that.

Here are the numbers to back up my comment. Please note that the numbers I use are gross weights. Weights I should not exceed. My Montana grosses out at 16960 lbs. Assume (which you shouldn't do) a 22% pin weight of 3731 lbs. That leaves a remaining gross weight on the axles of 13229 lbs. Based on the load v psi ratings for the 614's I only need to run 95 psi. Anything over that just makes the sidewalls flex less, allowing for less road shock absorbtion, inducing harsher ride. That being said, I run mine at 100 psi.

These are the load v psi ratings from Goodyear:
3300 lbs @ 90 psi x 4 = 13200 lbs
3415 lbs @ 95 psi x 4 = 13660 lbs
3550 lbs @ 100 psi x 4 = 14200 lbs
3675 lbs @ 105 psi x 4 = 14700 lbs
3750 lbs @ 110 psi x 4 = 15000 lbs

Based on these numbers, if you HAVE to run 110 psi because of your RV weight, you are exceeding axle rating and your gross weight rating. Also based on these numbers, most of us should never HAVE to run anything over 100 psi.

I know everybody has their own opinion about this but I truly believe most of us are unnecessarily inducing a harsh ride for our RV's.

I await the can of worms.

10-28-2016, 11:28 AM	#15
JABURKHOLDER Montana Master Join Date: May 2016 Location: Cuyahoga Falls Posts: 699 M.O.C. #18572	I know a lot has been said about G614's. I also know a lot has been said about what air pressure to run in those tires. I switched to 614's this past jul and I am very happy with them. I want to comment about pressure. With the "china bombs" you HAD to run max psi (80) just to support our heavy Montanas. With the 614's you do not HAVE to run max psi (110). I truly believe that most folks, including myself, are running these tire at a higher pressure than needed thereby creating a harsher ride for the RV. Things get bounced around enough without adding to that. Here are the numbers to back up my comment. Please note that the numbers I use are gross weights. Weights I should not exceed. My Montana grosses out at 16960 lbs. Assume (which you shouldn't do) a 22% pin weight of 3731 lbs. That leaves a remaining gross weight on the axles of 13229 lbs. Based on the load v psi ratings for the 614's I only need to run 95 psi. Anything over that just makes the sidewalls flex less, allowing for less road shock absorbtion, inducing harsher ride. That being said, I run mine at 100 psi. These are the load v psi ratings from Goodyear: 3300 lbs @ 90 psi x 4 = 13200 lbs 3415 lbs @ 95 psi x 4 = 13660 lbs 3550 lbs @ 100 psi x 4 = 14200 lbs 3675 lbs @ 105 psi x 4 = 14700 lbs 3750 lbs @ 110 psi x 4 = 15000 lbs Based on these numbers, if you HAVE to run 110 psi because of your RV weight, you are exceeding axle rating and your gross weight rating. Also based on these numbers, most of us should never HAVE to run anything over 100 psi. I know everybody has their own opinion about this but I truly believe most of us are unnecessarily inducing a harsh ride for our RV's. I await the can of worms. __________________ ATC/NAC Jerry A. Burkholder, USN (RET.) Rule #1. The Chief is always right. Rule #2. When in doubt, refer to rule #1.