At Spartan class this week, I learned a ton of new and interesting things, but one of the most useful is that the bulge in your tires are part of your suspension.OK, OK, I know that hundreds of you have been saying that your tires are an important part of your suspension, but I've never heard anyone specifically say that the bulge constitutes an important part. Of course this makes perfect sense. After all, did you know that your tire width is measured at the outside of the bulge:In class, we weighed our coaches on each corner and then looked up the charts to determine the exact PSI to set our tires. Mine was 10 pounds over inflated on the steer tires and 20 pounds over inflated on the tags so I let out air to get them to the proper pressure.After a four hour drive, I'm happy to report that it made a HUGE difference in ride comfort. The tire and brake instructor explained that the bulge takes the first shocks and the suspension is designed to work with the tire bulge to absorb and react to bumps and vibrations. If you needed another motivation to weigh your coach, I can only encourage you to do so and set those pressures properly. In addition to a better ride, you'll get better traction and braking as well.

Yes good info. Just Remember that that you need to inflate to the heaviest weight on an axel for both sides. Better said if one side calls for 92 lbs. and the other calls for 96 use the 96 for that axil.Bill

It has been said time and time again on here that the correct pressure for a tire is based on the weight that tire is supporting. But there are still those who air up their tires to the max number stated on the side wall regardless of the weight.

I know I can go to a Cat Scale to get the weight of my rig. But where can I go to get the exact weight on each tire?

Thats the whole point behind pneumatic tires. Otherwise we would use solid tires as they would last longer and no risk of a blow out.Of course the trade off of smooth ride by dropping the pressure is less efficency. That's why semi tire go up into the 100psi range. They don't care if the driver is comfortable but they do care about the mpg.

Don't fight the bulge | Good Sam Community

18 Replies

mpierce
Explorer
Aug 09, 2015
TucsonJim wrote:
I know I can go to a Cat Scale to get the weight of my rig. But where can I go to get the exact weight on each tire?

Go thru small towns. Look for the farm supply elevators, fertilizer dealers. They often have outdoor scales, that will also let you drive to the side, thus only weighing one side at a time.

Some will charge, others will not. If they are busy, don't bother them.

My local one here leaves the scale on all the time, allowing it to be used at night. They have a readout pointed outside so you can see it.
Kaz
Explorer
Aug 09, 2015
Darn. When I saw "Don't fight the bulge..." I thought you were going to tell me that my paunch is nothing to worry about. Sort of like, "A waist is a terrible thing to mind."

Oh well, good info about tires. Thanks.

Skip
wa8yxm
Explorer III
Aug 08, 2015
Remember many years ago (not all that many to a 60+ year old) the Ford Roll-a-matics (Ford Explorers with Firestone tires)

Ford blamed Firestone for it... I do not.

Well I will not go into the full reason but here is part of it.

FORD, knowning that folks bought these SUV's to replace the family Grocery Getter Wagon.. Recommended a tire pressure five PSI lower than what Firestone wanted. This was to increase that bulge and add to the "Springiness" of the tire so you got a smoother ride.

Again there is more.. but not today or in this thread.
valhalla360
Navigator
Aug 08, 2015
holstein13 wrote:
valhalla360 wrote:
Of course the trade off of smooth ride by dropping the pressure is less efficiency. That's why semi tire go up into the 100psi range. They don't care if the driver is comfortable but they do care about the mpg.
Intuitively, that would make a lot of sense, but I've seen no actually evidence to support this theory: http://www.popularmechanics.com/cars/a940/4199963/

Our instructor did say that this is not true or if it is true, it's negligible.

The flaw in your quoted article is they are taking the pressure beyond the tire manufacturers recommendation. A much different situation.

As far as the exact milage you will get, it is generally a small difference. I was sharing the idea behind it. As the owner operator, the slight loss in MPG may be well worth it to you.
topflite51
Explorer
Aug 08, 2015
mtrumpet wrote:
I wish I could find a place in my area where I could weigh all four corners. I've looked all over around here. So far, no such luck.
Have you tried this CAT scale directory.
mtrumpet
Explorer
Aug 08, 2015
I wish I could find a place in my area where I could weigh all four corners. I've looked all over around here. So far, no such luck.
holstein13
Explorer II
Aug 08, 2015
ncrowley wrote:
When I took my Freightliner class, he recommend 10 pounds over the pressure you needed for the heavier side (use 4 cover weighing). That will make sure you OK if you put a little more in the coach. You can go to any of the Escapees locations to have the 4 corner weighing done.
10 pounds extra PSI makes a huge negative difference to comfort on my coach. I'd do everything in my power to try and get the four corners plus tag and get the proper weights for each axle. In my case, I'm already at the lower limit of weight for my chosen PSI rating so I can add hundreds of pounds of cargo without going to the next bracket.
ncrowley
Explorer II
Aug 08, 2015
When I took my Freightliner class, he recommend 10 pounds over the pressure you needed for the heavier side (use 4 cover weighing). That will make sure you OK if you put a little more in the coach. You can go to any of the Escapees locations to have the 4 corner weighing done.
holstein13
Explorer II
Aug 08, 2015
WILDEBILL308 wrote:
Yes good info. Just Remember that that you need to inflate to the heaviest weight on an axel for both sides. Better said if one side calls for 92 lbs. and the other calls for 96 use the 96 for that axil.
Bill
Yes, thanks for pointing this out. We went over that in class as well. Also, Michelin and Goodyear each present the duallies weight capacities differently.
holstein13
Explorer II
Aug 08, 2015
TucsonJim wrote:
I know I can go to a Cat Scale to get the weight of my rig. But where can I go to get the exact weight on each tire?
This has always been a challenge for me as well. I waited a year after getting my coach to finally have the opportunity to weigh each corner. I'd say go ahead and get on the Cat Scale for now and weight the front and back. That will be good enough to get started. Then find a rally where they are weighing each corner. You can also call your chassis manufacturer and ask them where to find a local scale.