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01-19-2017, 12:11 PM
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#1
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Senior Member
Join Date: Dec 2012
Posts: 254
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Tire advice?
So, I have to replace all 8 on my 1984 Airstream due to age this year.
Airstream spec for the 1984 Airstream 345 is steer, drive, and tag axles.
ASW(Aprox Standard Weight)= 14300# and GVWR of 16500#.
They state the front axle rating as 5000#.
The rear axle is a little confusing as they state and I quote, "CMA Rear Suspension, GAWR 11000#, Full Air Drive Axle GAWR 9840#, Tag Axle Rubber Torsion GAWR 3000#."
Kind of ambiguous....
It came stock in 1984 with Michelin 8R 19.5 tires with 8 ply, and I cannot find the specs for those anywhere!
Planning to go to 225/70 R 19.5 tires, as they will fit, and give a little increase in load rating F over currently available 8R19.5.
I am pretty sure I am going to buy Cooper Roadmasters.
Cooper Roadmaster Tires - All Positions
They maybe made in China, but they have a good reputation and Cooper are standing firmly behind them.
The ones I like are the Roadmaster RM170, and in F load rating they are 3640lb single and 3415lb dual, which exceeds the axle ratings by a good safety margin. I see no reason to go to the G rated version.
My issue is that I considering putting some traction tires on the drive axle, that have more bite than the pure circumferential grooved steer tires. You CANNOT fit chains on this MH.
In this tire life cycle we have plans to do Yellowstone, and several other Mountainous trips, and maybe Alaska. I have NO plans to drive in snowy weather, but "ship" happens!
I have been stuck in a previous tow rig(RWD BMW & Trailer) on less than 1" of snow on a street, and also on wet grass in a field, purely because I had Z rated tires with only circumferential grooved tires. I swapped to M&S rated tires after that, and never had an issue, even this day...
I would hate that to happen on a freeway up north with a sprinkle of snow, in a rig weighing 16500#! The fact that my rig has a tag axle taking some weight off the drive axle only exacerbates the issue!
The ones I am looking at are Roadmaster RM253 tires, which are M&S rated.
They cost more, and come with a slight risk of increased road noise, and if I just put them on teh drive axle, the issue of not being able to rotate them throughout the axles to equalize wear or minimize the issue of a flat and replacement.
Anyone have an opinion or thoughts on the the issue of traction tires?
Please note, this is not a discussion on where the tire is made!
Thanks.
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01-19-2017, 12:52 PM
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#2
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Senior Member
Join Date: Jul 2016
Posts: 3,284
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The first thing is the tread pattern on a truck is a lot closer to your m&s pattern on the car than you think.
The second thing is if you can't lift tag axle it won't matter. What will matter would be a positraction rearend of some kind. I can't imagine a motor home chassis manufacturer of that era offering a limited slip rearend of any kind.
I once got a four wheel drive pick up stuck crossing a dry bar ditch when one front wheel and one rear wheel couldn't get traction. All it would take for you to be hopelessly stuck would be one rear wheel slipping, for any reason, tag axle picking up weight for example.
I'm replacing 8R's on our coach with 225 Michelins.
__________________
Life is Good
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01-20-2017, 06:54 AM
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#3
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Senior Member
Vintage RV Owners Club Fleetwood Owners Club
Join Date: Mar 2013
Location: c above
Posts: 5,525
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JMO
I replaced my mismatched tires last year. There were Michelin, Bridgestone,Goodyears on my PA when I bought her. I replaced them all with Hankooks 225-70-19.5 F rated in front and G's on the rears and she rides and handles like a dream. First time out I was doing 70 before I new it, never had her that fast I usually do 58-60. Happy and they didn't break the bank. Keep her on pavement.
I might add I did get her stuck in mud and @ a slight incline at my brothers farm and had a hell of a time getting her out.
Tim,
__________________
1982 Pace Arrow P30 454
KarKaddy SS, Toad: 2009 Genesis
Tim, Joe and Lilly too. Mpls Minn.
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01-20-2017, 07:11 AM
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#4
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Senior Member
Join Date: Oct 2014
Location: Port Orchard, WA
Posts: 4,215
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Make sure that the larger tires you are considering will fit in the front wheel well when the wheel is turned to the stops in BOTH directions . . .
__________________
Scot & Laura Kellersberger, U.S. Army (ret)
Newmar 4 wheel drive Dutch Star 3891, SOLD
Now RV'ing on the water in a Trawler!
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01-20-2017, 03:50 PM
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#5
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Senior Member
Vintage RV Owners Club
Join Date: Dec 2016
Location: Auburn CA
Posts: 239
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Quote:
Originally Posted by Hit_the_Rhod
Make sure that the larger tires you are considering will fit in the front wheel well when the wheel is turned to the stops in BOTH directions . . .
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I just bought new tires for my rig. I had to put larger tires on because I was changing from 16.5 to 16 Wheels. the point is I had to adjust the inner wheel well to accommodate the new tires. My Revcon is front wheel drive
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Tom & Michele Smith
RVM151
1983 Revcon King33
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01-20-2017, 04:45 PM
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#6
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Senior Member
Join Date: Oct 2015
Location: Morris, IL.
Posts: 639
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70 series
It seems to me when I considered replacing my 8r 19.5's with the later style 70 series, I read the rim width was not satisfactory for the wider tire. I also didn't want a shorter tire for going over the bumps, I like a taller tire for rolling down the road. If I could find rims wide enough for the 245/70/19.5 tires, I would replace the steer ones since they are really close to the height of the 8r's. I put Hankooks on and am pleased with them, the price was really reasonable online, 6 for 1200.00 shipped 180.00 mounting and balance beads.
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1989 Champion LaSalle 34' 454 ci always doing something to it
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01-20-2017, 08:44 PM
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#7
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Senior Member
Join Date: Dec 2012
Posts: 254
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Thanks for the input.
To clarify, I have had 225/70 R 19.5 on the steer axle for 7 years, without issues.
I have heard that sometimes there is an issue with sidewall clearance on the dual axle and on Airstreams there can be an issue with clearance between the tag axle tire and wheel well, especially if the tag axle itself or wheel bearing is worn. I will be double checking that issue too.
Minimum wheel width is 6" for the 225 tires, and that is what I have in steel wheels. The Alcoa's were an option on the Airstream, and as a weird coincidence, I snagged 6x locally last year!
Even stranger, was that this set had production dates in 1983/4!
These will be what my new tires will be going on after a good clean up and polish job..
Note, the production date, and maximum load on these OEM wheels....
Even tho I have 8 wheels, it is normal and in fact important that the inner dually wheel is a steel wheel, as the studs are not long enough for 2x alloys!
So, here are the Roadmasters I am considering, to show the tread..
RM170:
RM 253:
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01-21-2017, 05:12 PM
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#8
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Senior Member
Join Date: Nov 2014
Posts: 473
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I switched from 8R19.5's to Gladiator 225/70R19.5's on my last MoHo. Worked very well, rode well. Just make sure you have enough space between the duals. If they're too close together rocks & debris can get stuck between the tires and wear them.
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2004 Country Coach Inspire Genoa
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01-21-2017, 05:28 PM
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#9
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Senior Member
Join Date: Oct 2006
Location: Rochester NY
Posts: 2,706
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Quote:
Originally Posted by Keyair
So, I have to replace all 8 on my 1984 Airstream due to age this year.
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Beautiful coach!
__________________
Don
'07 Winnebago Journey 34H - CAT C7, Koni's, MCU's, SS Bell Crank, Safe-T-Plus
'07 HHR Toad, SMI AFO, Blue OX
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01-21-2017, 06:43 PM
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#10
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Senior Member
Join Date: Dec 2012
Posts: 254
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Thanks Pusherman!
A loooog way to go yet. I have a restoration thread going here on the Vintage page, if you like a good yarn!.
Thanks for the input 429. Aware of the sidewall clearance issue on the duals. I believe its improved slightly by using the Alcoa on the outer wheel, and I also plan to put Centramatic balancers on all axles, which will push the wheel outboard even more...
In fact, the front set just arrived!
Because Airstream has the Tag axle mounted dish out, like the outboard drive wheel, it uses the same Centramatics on drive and tag.
Interestingly, Centramatic say there is no need to balance the tires, and if putting centramatics on axles where the tires were balanced 15k miles or more ago, the weights should be removed!
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01-21-2017, 08:21 PM
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#11
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Senior Member
Join Date: Jul 2016
Posts: 3,284
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I have run 19.5 tires on my C5500 from day one. Michelins go 50,000 and the Roadmasters go 20,000. The biggest disappointment was Yokohamas on the rear, just plain slick when wet, you can sprint car fifteen thousand pounds of work truck when the circumstances are just wrong. Lucy, the truck, just went over 270,000 miles so there have been quite a few sets of tires since late 2002 when I bought her new as a cab and chassis.
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Life is Good
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01-22-2017, 01:28 PM
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#12
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Senior Member
Winnebago Owners Club
Join Date: Jan 2014
Location: North Central Alberta
Posts: 193
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Quote:
Originally Posted by Wroughtnharv
----------Michelins go 50,000 and the Roadmasters go 20,000.------
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Ha. Somewhere in the back of my mind I have this formula... Michelins cost not quite twice as much but go three times farther.
So, if you are going to do the miles and keep the vehicle, buy Michelin.
__________________
2004 Winnebago Journey 36G 330Cat
2004 Grand Cherokee BlueOx towbar
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01-24-2017, 11:40 AM
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#13
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Senior Member
Join Date: Dec 2013
Location: Chicago Area
Posts: 1,285
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I would suggest that putting aggressive tread will only help in mud, and will not do much for snow. Snow traction requires a good rain tire, which usually means soft rubber and siped. Silica also helps. Aggressive treads tend to be noisy. Owning a FWD motorhome, I originally went for Bridgstone Revos on the front. Yes, of course they did great, but I discovered after putting Firestone Transforce on the front, that the more aggressive tread really didn't make a measurable difference in the snow. The Transforce did fine in the snow - way better than the Goodyears. It was just a matter of getting a good wet road tire, rather than specifically the tread pattern.
BTY: You stated no chains, but you may be able to use cable chains as they are much smaller than an actual chain. If you are really going to go into questionable areas, you can always invest in traction devices, such as special mats. Look on the off road websites.
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2004 AllegroBay 34XB Nov 2017 Banks, Front & Rear Trac bars, Konis
Sold:'83 Revcon Prince 31' FWD GM Performance 502 w/Edelbrock MPFI, Thorley Tri-Ys & Magnaflows, 4L85E 4 spd. Tested to exceed 100 mph.
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01-24-2017, 12:00 PM
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#14
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Senior Member
Commercial Member
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,780
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8-19.5 LR F (95 psi bias or 100 Radial) are rated 3,070 Dual
8-19.5 LR F (105 psi bias or 110 Radial) are rated 3,500 Single
According to my TRA yearbook from 1987. Numbers almost never changed year to year so the above should help understand your situation.
Comment please do not confuse GAWR with the actual load you have on one of your axles. Only to know facts are on scales.
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Retired Design & Quality Tire Eng. 40+ years experience. Recognized in the industry and in court as an expert in failed tire inspection as I have performed thousands of failed tire "autopsies".
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