Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 12-31-2014, 06:27 PM   #1
Senior Member
 
Join Date: Dec 2014
Posts: 1,666
Vexing tire question - apologies for the length

I need at least 4 new tires for my 2000 Holiday Rambler Endeavor 40PDB. This is the Freightliner XC chassis with CAT 3126B engine. The OE tires are Michelin XRV 255/80R22.5, load range G. The maximum load capacity of this tire is at 110 PSI. Originally, Monaco Coach specified operating tire pressures of 100 front, 90 rear. After many blowouts and lesser tire failures, the NHTSA directed a safety recall which required Monaco to change the basic tire pressure settings on the placard to 105/95. The GAWR for the front axle is exactly twice the maximum load capacity of the OE tire. I suspect, but cannot yet confirm, that the GAWR is being limited by the tires, not the chassis.

Based on similar experience with other vehicles, I am wary of running tires on a vehicle this large at the ragged edge of their load-bearing capacity. I see plenty of commentary in these forums about poor performance and reliability from both Michelin and Goodyear tires in this application. These companies, in my opinion, are two of the most reputable tire manufacturers in the world. It makes me think that the OE tire specification, which was a disaster from the start, is insufficient to meet the demands being placed upon it in this installation, even with the updated pressure settings.

From my research, I see that I can buy 275/70R22.5 tires in load range H from Goodyear, Firestone/Bridgestone, and others. They are slightly smaller in diameter. Revs per mile are about 548, compared to 541 for the OE size. Most speedometers are not accurate enough for this to be noticeable. They are significantly heavier than the OE tire, in the 95-100 pound range vs. 89 for the Michelins. Undoubtedly, the ride will be firmer. From my rough measurements of my current tires, I'm nearly certain that my current rear wheels have sufficient spacing for these tires in a dual configuration. The lowest pressure setting in the load inflation table is 400 pounds (per tire) greater than the rear GAWR, so there is no way of precisely matching the tire pressure to the load. It will be slightly overinflated. FWIW, the OE tires are the same way - the pressure spec is higher than required by the load inflation table. It looks like these heavier tires will work with a margin of safety that the OE tires do not provide.

The cost of 6 new tires being what it is, I have to ask if anyone else has been down this path. I know people feel more compelled to post about negative experiences, so I'm not surprised at the lack of glowing reviews for the OE-size tires.

Am I over-thinking this and worried about nothing? Will load range H tires be uncomfortably harsh?

Has anyone done this? Please share your experience.

Mike
__________________
Mike
slowmachine is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 12-31-2014, 06:47 PM   #2
Senior Member
 
cbeierl's Avatar
 
Winnebago Owners Club
Freightliner Owners Club
Join Date: Aug 2005
Location: Nashua, NH
Posts: 2,689
I replaced the OE Michelin XRV 255/80R22.5 LRG tires on my Vectra with Goodyear 275/70R22.5 LRH ones and I've been very happy with them. The original tires were in fact the limiting factor in the GAWR and I didn't like being at the upper limit of the tire's capacity. I can run the 275/70 tires at 95psi front and back and end up with a much better ride as well. Although the difference is indeed small I did have the ECM tweaked to adjust for changed rev/mi.
__________________
Chris Beierl

2005 Winnebago Vectra 36RD
cbeierl is online now   Reply With Quote
Old 12-31-2014, 07:21 PM   #3
Senior Member
 
Join Date: Dec 2014
Posts: 1,666
Thanks for that, cbeierl. Just what I was hoping for.

Mike
__________________
Mike
slowmachine is offline   Reply With Quote
Old 12-31-2014, 07:34 PM   #4
Senior Member
 
flynnwalter's Avatar
 
Join Date: Nov 2010
Location: Lake City, Florida
Posts: 450
Mike
We have the dreaded Monaco RR4R chassis with undersized trailing arms. We got the Source Engineering trailing arms as well as their Ride Enhancement Kit installed and still had a rough ride. It was due to a 2700 lb heavier passenger rear (discovered at Josams in Orlando via 4 corner weighing during an alignment after trailing arms installation. This heavy side required max air on rear tires, and made our 255/70R Goodyears ride like solid rubber tires. My buddy owns a tractor trailer repair facility and is very knowledgable about all things trucking. Under his direction we went up two tire sizes to Bridgestone Ecopia 295/75R trying to get tires that would hold more weight at less psi. We used Dynabeads for balancing and used his laptop to change the speedometer since the tires are 3.9" taller. He contacted Allison and was told there was no need to change anything with the transmission. No problems whatsoever and now our coach rides about as well as it can be made to. It is enjoyable now, and is much better than I had even hoped. MCC Monaco should never have made this coach/chassis, but OTOH if they hadn't then we could not have afforded a new Monaco at the time (or now) I can easily say I would not hesitate to go this route, but that's really not very scary for me having such a good buddy to lean on. Good luck!
__________________
Frank W. '09 Cayman 38 SBD '08 CRV
Lake City, Florida
flynnwalter is offline   Reply With Quote
Old 12-31-2014, 07:50 PM   #5
Senior Member
 
Join Date: Nov 2003
Location: Richmond Hill, GA USA
Posts: 707
In August 2009,I replaced my xrv 255x80x22.5 with Sumitomo 727 tires in the 275/70R22.5 size. The load range H vs the G's I removed gives more load carrying ability and/or the ability to run less tire pressure for better ride. I checked the dual spacing, and it is still good with the 275/70 size.

Pleased so far with the tires, ride, and handling. I do think they are a little stiffer than the xrv's, but I feel safer.

My coach is much heavier on the driver side front, so the original 255x80x22.5 tires were overloaded in that position.

Fred
__________________
Fred & Vicki
St. Augustine, Fl.
Fred Cooper is offline   Reply With Quote
Old 12-31-2014, 07:59 PM   #6
Senior Member
 
Mr_D's Avatar
 
Country Coach Owners Club
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
Quote:
Originally Posted by cbeierl View Post
I replaced the OE Michelin XRV 255/80R22.5 LRG tires on my Vectra with Goodyear 275/70R22.5 LRH ones and I've been very happy with them. The original tires were in fact the limiting factor in the GAWR and I didn't like being at the upper limit of the tire's capacity. I can run the 275/70 tires at 95psi front and back and end up with a much better ride as well. Although the difference is indeed small I did have the ECM tweaked to adjust for changed rev/mi.
Same here but I went to 305/70's in front on our DSDP, but that was to get the full rated axle capacity of the 14,600# axle that Newmar had Spartan install in 2004. The 275/70's were just not up to the weight, in fact neither was the 12,000# OEM front axle!
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
Mr_D is offline   Reply With Quote
Old 12-31-2014, 10:55 PM   #7
Senior Member
 
Papa_Jim's Avatar
 
Outdoors RV Owners Club
Join Date: Oct 2009
Location: Manitoba,Canada
Posts: 2,789
Here's a tool that I've found to be very helpful.

255/80-R22.5 vs 275/70-R22.5 Tire Comparison - Tire Size Calculator

My other comment regarding moving from G to H.

I replaced my Dunlop G steer tires with Bridestone H tires. While doing so, I was concerned that the ride would be harsher.

I was surprised to find out that the H tires provide a much smoother ride than the Gs!

The problem with all this is, I don't know if it's the tire brand or the change in load rating that made the difference.

I guess we'll never know.
__________________
2016 Creekside 23RKS
2012 Ram 2500 Laramie 4X4 Cummins 6.7L
Canada, eh?
Papa_Jim is offline   Reply With Quote
Old 01-01-2015, 06:51 AM   #8
Senior Member
 
jplante4's Avatar
 
Monaco Owners Club
Nor'easters Club
Join Date: Sep 2013
Location: Cape Cod Mass
Posts: 316
I replaced the 9R22.5 Goodyear that were on the Sahara when I bought it with Yokohama 255R75, load range H. Also a smaller diameter tire. I haven't gone far on them yet, but the ride seemed better than the GY on the trip home from the tire place.
__________________
Jerry & Jeanne
1996 Safari Sahara 35' - White Tiger
Cape Cod
jplante4 is offline   Reply With Quote
Old 01-01-2015, 01:07 PM   #9
Senior Member
 
GaryKD's Avatar
 
Newmar Owners Club
Join Date: Jul 2006
Location: Wellington, Florida
Posts: 13,599
Hi slowmachine,
If you are looking for more carrying capacity, consider the Michelin 275X70X22.5 load range J. That is what I have been running since I got this coach. With a 20K rear axle, the recommended PSI is 90. My front axle is 12.5K. The recommended PSI is 100. The ride is smooth/quiet and there is plenty of reserve in the tires.
__________________
Gary
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
The Avatar Is Many Times Around The USA
Nobody Knows Your Coach Like Somebody Who Owns One Just Like Yours
GaryKD is offline   Reply With Quote
Old 01-01-2015, 02:13 PM   #10
Senior Member
 
Join Date: Dec 2014
Posts: 1,666
Quote:
Originally Posted by GaryKD View Post
Hi slowmachine,
If you are looking for more carrying capacity, consider the Michelin 275X70X22.5 load range J. That is what I have been running since I got this coach. With a 20K rear axle, the recommended PSI is 90. My front axle is 12.5K. The recommended PSI is 100. The ride is smooth/quiet and there is plenty of reserve in the tires.

I have looked at this size from several tire manufacturers. My rear GAWR is 17,000. I don't want to make the rear end ride like concrete tires, and I don't want to compromise the braking capability. I am going to the nearest Freightliner repair center on Monday to discuss fitment, capability and suitability of the various options. I'm assuming that they will have access to the engineering data from FCCC that will tell me what I can get away with. I have a local independent shop that I am hoping to rely on for much of the heavy lifting once I decide on a course of action. When I get the input that I want from all of the subject matter experts, I will figure out who to trust with implementation. I'm itching to get on the road, but I need to know that what I am doing is safe and manageable.

Mike
__________________
Mike
slowmachine is offline   Reply With Quote
Old 01-01-2015, 03:04 PM   #11
Senior Member
 
Steve Ownby's Avatar
 
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 6,587
Quote:
Originally Posted by slowmachine View Post
I need at least 4 new tires for my 2000 Holiday Rambler Endeavor 40PDB. This is the Freightliner XC chassis with CAT 3126B engine. The OE tires are Michelin XRV 255/80R22.5, load range G. The maximum load capacity of this tire is at 110 PSI. Originally, Monaco Coach specified operating tire pressures of 100 front, 90 rear. After many blowouts and lesser tire failures, the NHTSA directed a safety recall which required Monaco to change the basic tire pressure settings on the placard to 105/95. The GAWR for the front axle is exactly twice the maximum load capacity of the OE tire. I suspect, but cannot yet confirm, that the GAWR is being limited by the tires, not the chassis.

Based on similar experience with other vehicles, I am wary of running tires on a vehicle this large at the ragged edge of their load-bearing capacity. I see plenty of commentary in these forums about poor performance and reliability from both Michelin and Goodyear tires in this application. These companies, in my opinion, are two of the most reputable tire manufacturers in the world. It makes me think that the OE tire specification, which was a disaster from the start, is insufficient to meet the demands being placed upon it in this installation, even with the updated pressure settings.

From my research, I see that I can buy 275/70R22.5 tires in load range H from Goodyear, Firestone/Bridgestone, and others. They are slightly smaller in diameter. Revs per mile are about 548, compared to 541 for the OE size. Most speedometers are not accurate enough for this to be noticeable. They are significantly heavier than the OE tire, in the 95-100 pound range vs. 89 for the Michelins. Undoubtedly, the ride will be firmer. From my rough measurements of my current tires, I'm nearly certain that my current rear wheels have sufficient spacing for these tires in a dual configuration. The lowest pressure setting in the load inflation table is 400 pounds (per tire) greater than the rear GAWR, so there is no way of precisely matching the tire pressure to the load. It will be slightly overinflated. FWIW, the OE tires are the same way - the pressure spec is higher than required by the load inflation table. It looks like these heavier tires will work with a margin of safety that the OE tires do not provide.

The cost of 6 new tires being what it is, I have to ask if anyone else has been down this path. I know people feel more compelled to post about negative experiences, so I'm not surprised at the lack of glowing reviews for the OE-size tires.

Am I over-thinking this and worried about nothing? Will load range H tires be uncomfortably harsh?

Has anyone done this? Please share your experience.

Mike

Congratulations on having the good sense to research what your options are. I would think that your ride would improve along with your margin of safety. You can lower your inflation pressure and still have more weight carrying capacity than your current setup. Don't worry about not being able to match your inflation exactly with your GVWR. The inflation tables list the minimum pressure to carry the weight an extra 5-10 psi will just give you a margin of safety.


Steve Ownby
Full time since '07
__________________
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 01-01-2015, 04:31 PM   #12
Senior Member
 
GaryKD's Avatar
 
Newmar Owners Club
Join Date: Jul 2006
Location: Wellington, Florida
Posts: 13,599
Hi slowmachine,
With a 17K rear axle, one can go to the minimum of 85 PSI on the load range L tires. for the L tires, 85 PSI is the minimum Michelin accepts regardless of how light the axle load is. Don't know if this makes the tires too hard for your coach. You're going about this the right way. Good luck.
__________________
Gary
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
The Avatar Is Many Times Around The USA
Nobody Knows Your Coach Like Somebody Who Owns One Just Like Yours
GaryKD is offline   Reply With Quote
Old 01-02-2015, 05:54 AM   #13
Senior Member
 
flynnwalter's Avatar
 
Join Date: Nov 2010
Location: Lake City, Florida
Posts: 450
Slowmachine
You have been advised about what psi you can use based upon axle ratings as well as the manufacturer's suggestions. But that does not take into account what your tires are actually carrying. Blowouts don't care what the axle rating is. Get a four corner weighing when you are loaded as for a long trip with full tanks so your coach will be as heavy as its ever likely to be. This is the only method that really tells you what you need to know. If you just weigh the rear axle, for example ours--which I admit is extreme, you would not know the passenger rear is 2700 lbs heavier than the driver rear. Just taking the total axle weight and dividing by the four tires and using the tire manufacturer's chart to find the psi would therefore leave the heavier passenger rear tires seriously under inflated--which is the number one cause for blowouts. Four corner weighings are hard to get and typically cannot be done at a public scale due to the coach leaning and skewing the weight. We got ours at Josams in Orlando. Many Monaco rallies have featured four corner weighings and with a bit of research you can find one. RVSEF RV Weighing
Otherwise you are just guessing. We certainly were shocked at our weight difference and the tech at Josams said lots of coaches are not the same weight side to side. Good luck.
__________________
Frank W. '09 Cayman 38 SBD '08 CRV
Lake City, Florida
flynnwalter is offline   Reply With Quote
Old 01-02-2015, 06:53 AM   #14
Senior Member
 
Join Date: Dec 2014
Posts: 1,666
I am curious about the side-to-side weight distribution. Both slides and the kitchen are on the left side. The MH is winterized and empty. I'm tempted to have it weighed as-is and use the numbers to help me distribute weight as I load it. When I'm finished with the basic load, I can take it back and fine-tune the results. There is a Pilot Travel Center about 28 miles from here that can do it. I can probably delay buying tires until I have actual numbers.

At the moment, my top priority is to reseal the roof seams. The roof is aluminum, and has a long, taped seam (Eternabond?) running lengthwise up the middle, and a side-to-side seam at each end of the center seam. I have a cover on it now, so water infiltration is not an immediate concern. I have an appointment next week to get the MH into a heated service bay and (much to my dislike) pay someone a ridiculous fee to do this. It's too cold here to do the roof in my yard, and I won't wait until April.

Mike
__________________
Mike
slowmachine is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Another dumb tire monitor question.. Engle MH-General Discussions & Problems 15 08-18-2014 07:13 PM
Another Michelin Tire question adonh Class A Motorhome Discussions 11 02-04-2014 05:59 PM
2005 Itasca Sunova awning brand & length question RTegarini Winnebago Industries Owner's Forum 4 01-27-2014 09:48 AM
Question about battery bank system and length of wire to purchase Jasper7821 RV Systems & Appliances 9 01-24-2014 02:48 PM
A question on Class A Tire conversion mark44004 Class A Motorhome Discussions 4 01-16-2014 02:25 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 08:55 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.