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Old 01-10-2013, 06:32 AM   #1
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Are these Tire Pressures "Normal"?

OK...Getting ready to pick up the Dutch Star with the following Axle ratings:

Front 14,200#
Drive 20,000#
Tag 10,000#

We are picking it up winterized so no water which is probably not an issue anyway with the tag axle. So, just for the sake of argument I was running numbers as if the axles were maxed out and equally balanced. Yes, I know about 4/6 corner weighing but I doubt I would be that hugely imbalanced with an unloaded MH to make any wheel weight higher than the average.

So, based on the tire pressure charts for Michelin, 305/70R22.5 LRL - XRV these are the "corner" tire weights and pressures I came up with.

Michelin North America RV Load & Inflation Tables

Front - 7,100# = 105 PSI
Drive - 10,000# = 80 PSI
Tag - 5,000# = 75 PSI (Minimum PSI)

These pressure setting numbers are RADICALLY different compared to my Winnebago where water and fuel are over the rear axle and have the rear tires at higher pressures. Seeing these numbers surprised me quite a bit. Am I making some stupid math error or missing something? Are these numbers typical for folks with similar tires?

These are replacing the same tires sizes from the Spartan factory.

I was just surprised at how "low" these numbers are. Thanks for double checking me.
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Old 01-10-2013, 06:46 AM   #2
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My new MH came with tire pressures at 100 lb when delivered after I had it loaded with my stuff fronts are 90lb and rears are 85lb have been there for 10 years I have owned it.
Replaced fronts last year because of wear and still on same four rears.
Your pressures will change when you have coach weight for yourself.
Did you have Goodyear or Michelin on older coach different company may have different pressures.
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Old 01-10-2013, 06:49 AM   #3
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Your chart reading skills are spot on. I concur with your pressures. Many people would council you to increase all the pressures by 5 psi or so to allow for any side to side imbalance, but since the coach is not packed and you are basing the weights on GAWR, I think you are good to go. I recommend a TPMS if you don't have one already.

Congratulations on your new ride. May you enjoy it in safety.
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Old 01-10-2013, 07:39 AM   #4
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Quote:
Originally Posted by "007" View Post
My new MH came with tire pressures at 100 lb when delivered after I had it loaded with my stuff fronts are 90lb and rears are 85lb have been there for 10 years I have owned it.
Replaced fronts last year because of wear and still on same four rears.
Your pressures will change when you have coach weight for yourself.
Did you have Goodyear or Michelin on older coach different company may have different pressures.
Came with and getting Michelin. I double checked with Spartan Chassis this morning and they verified it was shipped with the Michelin 305/70Rs.

I am starting the think that the tire/axle capacities will not be hard at all to stay below maxing them out. I may find that once we load it out these max pressures are like yours. Set and forget. That would be especially true for the tag since I'm already at the minimum chart weights.

Thanks!
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Old 01-10-2013, 07:47 AM   #5
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Quote:
Originally Posted by Steve Ownby View Post
Your chart reading skills are spot on. I concur with your pressures. Many people would council you to increase all the pressures by 5 psi or so to allow for any side to side imbalance, but since the coach is not packed and you are basing the weights on GAWR, I think you are good to go. I recommend a TPMS if you don't have one already.

Congratulations on your new ride. May you enjoy it in safety.
As I mentioned to 007, I may never have to change these initial pressure setting used for delivery but I will follow up with proper corner weights as I get it loaded out. You know I can't help my pernickety ways about weight and balance. LOL

I already ordered 2 more sensors and relay antenna from TST for the extra wheels. I will use my current set of 6 on the drive and tag axles till the new ones come in. TST recommended that because I would be running so light on the tires in the back I may not feel any problems while a front tire issue would be much more likely to be felt.

Sandee and I are already scheduled for the Spartan Chassis owner's training at the Charlotte factory from May 6-10. They will weigh us so we can really fine tune "normal" numbers. We are pretty excited to get that training which covers issues from driving skills through maintenance. I have a LOT to learn!

Thanks!
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