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Author Topic: wider front tires?  (Read 537 times)

Dwight Lakusta

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wider front tires?
« on: May 19, 2019, 03:38:41 AM »
Has anyone ever put wider front tires to get more weight capacity and more weight displacement in soft areas?
2003 Beaver Marquis Ruby 40, 3 slides, C12, 505HP. Current unit.
2008 Newmar Dutch Star, 40, 4 slides, 8.9 ISL, 400HP.
2000 Monaco Windsor, 40, 2 slide, 8.3 ISC, 330HP.

David T. Richelderfer

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Re: wider front tires?
« Reply #1 on: May 19, 2019, 03:49:15 AM »
Yes.  We replaced the 295/80R22.5 steering tires with 315/80R22.5 tires because the coach's weight was right at the upper limit of the 295's weight bearing capacity and the 295s were showing stress cracks.  The weight bearing capacity of the 295s is about 8,250 pounds; the 315s just over 9,000 pounds - both at maximum pressure.
David, Leslie & JB
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Dwight Lakusta

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Re: wider front tires?
« Reply #2 on: May 19, 2019, 05:44:20 AM »
Yes.  We replaced the 295/80R22.5 steering tires with 315/80R22.5 tires because the coach's weight was right at the upper limit of the 295's weight bearing capacity and the 295s were showing stress cracks.  The weight bearing capacity of the 295s is about 8,250 pounds; the 315s just over 9,000 pounds - both at maximum pressure.

Oh wow. No rubbing issues at all? Is that tire wider?
2003 Beaver Marquis Ruby 40, 3 slides, C12, 505HP. Current unit.
2008 Newmar Dutch Star, 40, 4 slides, 8.9 ISL, 400HP.
2000 Monaco Windsor, 40, 2 slide, 8.3 ISC, 330HP.

Mike Shumack

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Re: wider front tires?
« Reply #3 on: May 19, 2019, 11:47:48 AM »
Yes.  We replaced the 295/80R22.5 steering tires with 315/80R22.5 tires because the coach's weight was right at the upper limit of the 295's weight bearing capacity and the 295s were showing stress cracks.  The weight bearing capacity of the 295s is about 8,250 pounds; the 315s just over 9,000 pounds - both at maximum pressure.


Note that Michelin has reduced the load capacity for the 315/80R if it is mounted on a 8.25" wide tire. Our wheels are 8.25" wide (at least on my '05 Patriot).
 
My coach has the 315s on front and the 295s on the rear - but I have considered switching back to the 295s in front when the next tire change is due. Reason - to have all matching sizes so my (295/80R) spare will fit any position and because the 295 size is less expensive. I don't see a big difference in load capacity at the 7,000 lb rating (our front axles are rated for 15,300) and the difference in air pressure at that weight is only 5 psi.

Is there a compelling reason the stay with the 315s on the front?

EDIT: correction on typo - our stock rims are 8.25" wide
« Last Edit: May 19, 2019, 03:31:37 PM by Mike Shumack »
- Mike

'05 Beaver Patriot Thunder 525, Vicksburg, CAT C13, Allison 4000MH, HydraLift
Orlando, FL
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David T. Richelderfer

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Re: wider front tires?
« Reply #4 on: May 19, 2019, 03:22:08 PM »
My compelling reason was, as I stated but here in more detail, the coach's steering axle weight full of fuel and water was right at or slightly above the weight bearing capacity of the Michelin 295s at their maximum pressure of 120 psi.  And the tires were showing stress cracks.  Also, my replacement 315s are Dunlops, not Michelin.  Five of the six rear tires are Toyos, one is Michelin.  That's another story.

The coach has the wider rims so I get "full value" of the Dunlop 315s, that being a weight bearing capacity of 9,090 lbs (if I remember that correctly) at 130 psi.  And the maximum pressure rating for the rims is 130 psi.

The morning cold pressures I use are 125 psi, 115 psi, and 110 psi going front to back on the three axles.  Interestingly, within an hour the 315s on the front will rise to 140 to 145 psi according to my TPMS.
David, Leslie & JB
Towing a black Chevy Avalanche
Using a Blackhawk Towbar & Evenbrake
RF Mogul Eagle 3 for DISH TV
Go Beavers, OSU Class of '71
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Mike Shumack

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Re: wider front tires?
« Reply #5 on: May 19, 2019, 03:40:57 PM »
Hi Dave.
So you have the wider rims - that's good. And a little more tread width on the pavement is nice too for added traction  ;)

FWIW - The 295 tires and 315 tires have a weight capacity/ratings above what our Coaches can handle. We can only put 7,650 lbs max on each tire without exceeding the axle and wheel load capacity.
- Mike

'05 Beaver Patriot Thunder 525, Vicksburg, CAT C13, Allison 4000MH, HydraLift
Orlando, FL

Dwight Lakusta

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Re: wider front tires?
« Reply #6 on: May 19, 2019, 04:28:50 PM »
My compelling reason was, as I stated but here in more detail, the coach's steering axle weight full of fuel and water was right at or slightly above the weight bearing capacity of the Michelin 295s at their maximum pressure of 120 psi.  And the tires were showing stress cracks.  Also, my replacement 315s are Dunlops, not Michelin.  Five of the six rear tires are Toyos, one is Michelin.  That's another story.

The coach has the wider rims so I get "full value" of the Dunlop 315s, that being a weight bearing capacity of 9,090 lbs (if I remember that correctly) at 130 psi.  And the maximum pressure rating for the rims is 130 psi.

The morning cold pressures I use are 125 psi, 115 psi, and 110 psi going front to back on the three axles.  Interestingly, within an hour the 315s on the front will rise to 140 to 145 psi according to my TPMS.

Does your sticker on the wall say you have the 9” wheels? Or does it say 8.25 and you actually have The 9?
2003 Beaver Marquis Ruby 40, 3 slides, C12, 505HP. Current unit.
2008 Newmar Dutch Star, 40, 4 slides, 8.9 ISL, 400HP.
2000 Monaco Windsor, 40, 2 slide, 8.3 ISC, 330HP.

Bill Lampkin

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Re: wider front tires?
« Reply #7 on: May 19, 2019, 04:45:28 PM »
If front axle weights are a concern, One option might be to reduce tag axle pressure (not tag tire pressure) just a bit so more weight would be on the drive axle; less weight on the steers. Its a balancing act, for sure, but cheaper than 315's! 
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

Bill Lampkin

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Re: wider front tires?
« Reply #8 on: May 19, 2019, 04:53:44 PM »
Excellent info from Michelin on RV tires. Sidewall cracking see pg 8.

https://www.michelinb2b.com/wps/b2bcontent/PDF/RV_Tires_Brochure.pdf
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

David T. Richelderfer

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Re: wider front tires?
« Reply #9 on: May 20, 2019, 03:44:05 AM »
When I have had tires changed I looked at the rims.  They were clearly stamped 9" - 130 psi maximum.

Actually, we axle-weighed the coach not long after purchasing it.  That's when I discovered the steering axle weighed over 16k lbs and very close to the 295's weight bearing capacity at 120 psi.  Soon after that weighing, I reduced the "tag weight" by reducing the "push-down" pressure noted on the dial found inside the rear engine door.  I think I reduced the dial pressure from near 35 lbs to under 30.  I have not had/taken the opportunity to re-weigh the axles since then.

Yes, I have read the maximum load on the steering axle is 15,000 lbs or so.

Virtually everything I know about the technicals of our Marquis Sapphire has been garnered from this Forum.  It's worth far more than every penny I spend on it!  I spend hours every week and enjoy reading new and old threads.
David, Leslie & JB
Towing a black Chevy Avalanche
Using a Blackhawk Towbar & Evenbrake
RF Mogul Eagle 3 for DISH TV
Go Beavers, OSU Class of '71
RVing since 1973
Constitutionalists, Golfers & Capitalists
Your luck is the residue of your management
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Dwight Lakusta

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Re: wider front tires?
« Reply #10 on: May 22, 2019, 05:42:10 AM »
I wish I had more time to be on the forums as well.  Love being on here.
2003 Beaver Marquis Ruby 40, 3 slides, C12, 505HP. Current unit.
2008 Newmar Dutch Star, 40, 4 slides, 8.9 ISL, 400HP.
2000 Monaco Windsor, 40, 2 slide, 8.3 ISC, 330HP.