Newell Gurus

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I’m a new to me owner of coach 590
New 315/80 22.5 michelin tires

Yesterday on maiden trip, had someone abruptly change lanes in front of me that prompted heavy braking.  The tag axle tires locked up and slide a short distance putting a noticeable flat spot in both sides of tag axle tires.   

I went to cat scales and weighed several times with various axles and setting of tag switch.

After reviewing data and checking Michelins website for recommended tire pressures for various weights, I have a few questions

1- is it ok to run with tag switch in up position which increases weight on tag axle
2- according to the chart, I should run 130 psi in steer tires, 90 in drive and tag tires.  Does this seem reasonable with weights?
3 Are those pressures cold psi or operating pressures?  My tire pressures in go up 20-25psi from 40 degree cold to 70 degree afternoon interstate driving.   For example, do I start out with steers at 110 so they are 130ish at operating temp or start at 130 and they operate at 150 psi?


Below are my weights full of fuel, 3/4 tank of water , empty black

Tag switch in middle position
This is position it was in when locked up and flatspotted tag axle tires
Steers 17780
Drive 24980
Tag 9780

Tag switch in bottom (increase traction) location I guess used for tight turns or icey roads?

Steers 16800
Drive 32600
Tag 3360


Tag switch up (decrease traction ) 
This is position looks to me to better balance rv and increase stopping power
Any problem running like this all the time?

Steers 18040 
Drive 22880
Tag 11560




Just for reference, I had my tire pressures yesterday (my first day out with Newell)

Steers 130psi 39 degrees in am—— 151psi 77 degrees operating by 2pm traveling on 95 interstate 
Drives 120 psi cold——— 135 psi 72 degrees operating
Tag 120 psi cold ——— 137 psi. 84 degrees which I guess where higher than drives due to heated air from drives being directly in front of them.  This was after flatspotting and i had tag switch in up position the rest of day


This morning it is 40 degrees and I was thinking to start out with
120psi in steers cold and 100 in drives and tags cold to see how it does unless you guys recommend differently 

Thankyou in advance
David and Mimi
Below are the scale tickets.   This is with the toad disconnected

The notebook page is psi - tire temps at operating temperature on 95 running 65mph
David,

Do you have 318s or 365 on front?

I always measure pressures with cool but not cold tires. I run 110 in both tag and drive tires. I also have 110 in steer but I have 365s... would need higher if 318s.

I don’t like the idea of driving with tags switch in either active position. I see your logic and cannot refute it but it makes me uncomfortable. Maybe someone with more knowledge can weigh in.

Bill
An emergency stop will flatten the tag tires because they are not connected to the ABS system as are the other axles. Twice I had to replace mine. With 365s on the front, I ran with 110 psi cold all around. With 318s on the front, I would set them at 130 and not drive over 65 mph.
David, in the past, a few Newell owners have published the actual axle weights. #579, also a 2001 listed his weight with full water and fuel and 2 people, empty waste tanks as 17,200 steer, 23,260 drive and 9,600 tag. I presume your GAWR's are the same as Chester's at 18,000 steer, 26,000 drive and 12,000 tag.

He had experienced the same issue with flat spotting the tag tires. http://newellgurus.com/showthread.php?ti...spot+tires I would not recommend driving with the switch in the 'increased traction' position since it puts the front tires just over the GAWR and the front tires seem to be the most likely to have issues due to overweight conditions. I am not even certain that added the additional ton of weight to the tags would prevent them from locking up in a panic stop.

As noted above, some of the Newells in that era did not have anti-lock brake circuits on the tag axle.

Always check tire pressure when cold and do not adjust tire pressure when they are hot, per the tire manufacturers. All tires will increase in pressure as they get hot from running, particularly at high speeds. A 20+ psi pressure increase between cold and hot is not uncommon on truck tires.
a follow up question on abs. the tag on my 99 clearly has an abs sensor on it. so you are saying that it doesnt function? it clearly does show up in the abs codes.

tom
Apparently some did and some didn't. If it shows up on your abs codes, I would tend to think it is functional. As I recall, Richard has sensors on his tag but they are non functional as there is nothing to plug into them. Next time you are messing around with it, you might check to verify that it is actually wired into the system.
it is for sure wired in because i have a abs light that was on and the code was drivers side tag. i have traced the wire to the front plug and it is labeled and in the plug on the control box.

tom
Great questions

This is one of the most important safety issues we can and need to monitor.

I would advise the middle position, as this seams to have a better weight distribution on each axle and not overloading the front or drive that the other positions offer. I would believe the other 2 positions are for slow speed maneuvers, not for travel mode.

Always review PSI when cold, or starting your trip. Never warm or hot, except with a TPS, see below.

Review Michelin's Tire pressure recommendations for axle weights and tire size.

https://www.michelintruck.com/michelintr...lation.pdf

Escapee's group has a teem that will measure each wheel and the weight it is putting down. This will help you not only each axle but right to left loading of you coach. This team travels to all of there events nation wide, and perform the service for a nominal cost. They also put on a 2 hour seminar on Tire safety and awareness, stressing on knowing how to read date codes and keeping your tires on average no more than 6 years old. BTW, I just purchased 4 drive tires and they were about 6 months old, when installed, by date code. #$#@#$. These folks will also test your Tire pressure gauge and let you know how accurate it is. Some can be off 3% to 5%. Being consistent with the same Gauge will do, until you can verify its accuracy

Lastly Tire pressure monitors (TPS) on each wheel will give you a higher level of comfort. They will warn you of number of things including temp rise, or pressure loss. You can even monitor your Toad/trailer. Not that its likely to have a problem, but you would also never know if it did until some one flags you down because of the mess you left on the road when the tire exploded on a hot humid day in august going thru a construction zone in Austin TX with no where to pull over. (kinda specific?) Ok that happened to me, towing my box trailer.
Sorry I didn’t say in opening post, I’m running the Michelin 315/80 22.5 in all positions.

Thankyou guys for your insight.

I’m going to replace these 2 tag tires. Hate I messed them up but it was a lesson learned.

These tires cost me 1,000 each installed. Is that the normal going rate?

Is there a better deal or discount program? Who do you guys use when purchasing these tires?

I’m in Savannah today, then heading up 95 into North Carolina.
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