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Topic: Tires for my 88 ORED, with 7.5 wheels  (Read 1249 times) previous topic - next topic

Tires for my 88 ORED, with 7.5 wheels

How wide and how large works well?  I have 255/70 now and would like 275/80 .  I need a little more gear.
 Do these fit? Not sure on the OE tire tag .
 Thanks,MM

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #1 –
Mine had 295/75 on it when I got it. 265/75 may be a better choice as I don't have sqaut for clearances in the front for a trailing arm suspension to deflect backwards. My sweet spot is about 2200 rpm when pulling grades at 65 mph with a 4.11 ratio. But no toad, and about 22k lbs. I am going with yo Mama's for the new tires as I have had only good experience with that brand.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #2 –
Let's start out with what was OE size (the GVWR plaque near driver's area.  I have seen many coaches fit with non-OE size tires.

Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #3 –
There seems to be a few off these running around , I was hoping to see what others are running.
  The OE tag is 9r/ The wheels are 7.5.
    I need some larger IPR (inches per revolution) tires to get a little more speed and get closer to  my target  of 2400/ = 68mph.  275/80 hits pretty close . (69)
 I dont want the tires to hit the body or lose too much acceleration /braking performance.  M Y current tires are short 255/70.
 2400= 63mph

  It drives really well  with these 70series.  How many have 8o series?
 TIA, MM
  FWIW with  265/75 ---2200 = 60MPH  , 2400 = 66

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #4 –
Quote from: wolfe10 –
Let's start out with what was OE size (the GVWR plaque near driver's area.  I have seen many coaches fit with non-OE size tires.


Brett you made me go look, Beam alarm specs which are copies of FT specs, show 10R for the 300hp. Data plate shows 275/80 on 7.5" rims. Thanks. I need to find a level spot today and check my ride height. My speedometer may be off also.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #5 –
Per the Michelin guide, only one revolution per mile difference between 10R and 275/80R22.5. But 10R from them come in Load range F and G, while 275's are H (all this in Michelin XZE series).
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #6 –
The 295/75 are closest to the OE roll out. of 40in,  Do these fit on the 7.5 wheels OK ?

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #7 –
The Michelin book and they do show the 275/80 as OK on 7.5" wheels.

Toyo shows their 295/75 as needing 8.25" wheels.

But, check on the tire manufacturer's website for the specific series tires you are considering.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #8 –
My best advice is get in contact with the tire manf. Mine had 295/75 on 7.5 rims when I got it running at 63% of rated load after I weighed the front and rear with a 3/4 full water tank in the front weighed in at around 7k at the local grain elevator.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #9 –
Phred check the ride height valves for repeatability.

Dump and fill three times,  measure bumper height.

Coach "bump" steers.  Not returning to exact ride height will have coach not going straight.

Look in the Oshkosh manual for the steering box spool centering info.

Symptom of not being centered was that the coach would sometimes seem to head for the edge of the road for no reason.

Three hour bench job to recenter the Spicer 710 box.  Must be removed.

Fixed countless coaches for the wander from all brands as everyone uses the same box then.
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #10 –
 Thanks Brett, will do .

Phred, The most important question; How did/does  it drive with the 295 s on it?
 I posted my ride height here. Ored ride height
 Thanks,MM

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #11 –
Drove without much steering input, got good at dodging the potholes by running right side over on the shoulder when I seen them coming. Adjusted tire pressure down closer to manf. load chart about mid-trip home. Held the road well thru the crosswinds of new mexico and Oklahoma.  Maybe I am worrying too much about the clearance, because the 295's did not hit or rub when the front end went airborne on a bridge on the west side of OKC.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #12 –
 Thanks Phred,
 Any insight as to why the 9 R  tires at  and the 295/75 , both 40  in tall would have a 15# weight variance?  Is the 9R that much narrower?    The section width shows  10.5 for the 9R and 12 for the 295.    The larger tire 295 also has about 900# more load capacity.  Both about the same price.  I will probably get the heavier tire based on Phred's test.
  Is this the tire that the rest of the old DP are using?  Thanks,MM 

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #13 –
I suppose that I'm just too lazy to worry about turns per mile and all of that. I don't want the tires to rub the air bag plates when I make a sharp turn. I don't want them to rub the body above the wheels at a sharp bridge transition. Other than that a turn or three per mile or whatever is negated by surface temperature, wind direction, road surface, elevation, weather, up or down hill, etc.,etc...What I set up for today in 65 degrees with bright sunshine in level Illinois is going to change tomorrow as I head south and hit the rolling hills of Southern Illinois. Supposed to be in the mid 80's by the weekend so that changes etc. Variables are just that: variable, Not enough time in my life to worry about the little stuff.
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #14 –
As Mike is seeing [as  I did on a 83 wanderlodge] is that Federal speed limit of 55 mph between 1973 and 1987 influenced many coach manufacturers choice of engines and transmissions . As they though your top cruising speed would be 55 mph, they installed gear ratios that would keep the engines in the proper torque ranges at that speed. Only real cheap fix is to get taller tires to make up for the short gearing. My wanderlodge 3208 na was wound out at 2780 rpm at 66 mph, not real practical to run at for extended periods.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #15 –
My '81 FTX triple nickel ran 70 mph at 3.000 rpm. My brother accused me of trying to blow it up so I could put a bigger engine in it. Ran it like a 36 hp. Volks pedal to the metal from San Bernardino to the Phoenix race track for 15 years. Still runs great.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean
 

Re: Tires for my 88 ORED, with 7.5 wheels

Reply #16 –
Cats are not Cummins. Even on dead flat land would run over 200 F. at that speed, on a slight hill would drop to 55 mph and temps would start to rise. Of course, coach weighted 30500 lbs with 210 hp and 500 ft/lbs.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.