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Topic: Tire size (Read 764 times) previous topic - next topic

Tire size

Has anyone run 275 80's in day the rear axle and 295 75's on the front? Does it mess with the ABS system?
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Tire size

Reply #1 –
Since the tires sizes are only off in diameter one revolution per mile, this is less than a worn vs new tire. Can't imagine any difference to the ABS. Differences in brands will also make a diameter difference.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Tire size

Reply #2 –
125.11 in. circumference on the 80, 125.42 on the 75 only .2% difference. Like Pierce says not going to affect the system.
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: Tire size

Reply #3 –
Pierce That's kind of what I was thinking. Just wondering if anyone has actually done it. My fronts are year old 295's, fixing to replace the 7 year old tires this mo. May go back with the correct size.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Tire size

Reply #4 –
Quote from: bbeane –
Pierce That's kind of what I was thinking. Just wondering if anyone has actually done it. My fronts are year old 295's, fixing to replace the 7 year old tires this mo. May go back with the correct size.
I don't think there is a "correct" size, just a difference in aspect ratio. Bottom line is the 295's are slightly wider but for all practical purposes, the same diameter. Unless you carry a spare, the 295's will be easier to replace if you are stuck somewhere. We are all 295/75 on our coach.

Should not be a ride difference in aspect ratio as each manufacturer has a little different construction for each brand. We even have a couple of Firestones on one side in the rear.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Tire size

Reply #5 –
Does increasing the front tire size run the risk of hitting the air bag metal bottom plate?

Re: Tire size

Reply #6 –
Quote from: Barry & Cindy –
Does increasing the front tire size run the risk of hitting the air bag metal bottom plate?
.1 in. difference in diameter.  .79 in. width difference. If it was an issue adjust stops.
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: Tire size

Reply #7 –
Quote from: Barry & Cindy –
Does increasing the front tire size run the risk of hitting the air bag metal bottom plate?
mine do touch a bit on a tight turn not enough to hurt any thing.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Tire size

Reply #8 –
Quote from: Barry & Cindy –
Does increasing the front tire size run the risk of hitting the air bag metal bottom plate?
It apparently did on my coach.  According to records, previous owner installed new 295's all around, then a month later replaced the front tires with 275's.  The bottom plates of the air bags had paint polished off when I bought the coach. 
Jan & Richard Witt
1999 U-320  36ft WTFE
Build Number: 5478 Motorcade: 16599
2011 Jeep Wrangler Unlimited w/Air Force One
Jan: NO5U, Richard:KA5RIW
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Re: Tire size

Reply #9 –
Quote from: Barry & Cindy –
Does increasing the front tire size run the risk of hitting the air bag metal bottom plate?
In certain attitudes, one of the tires polishes the bottom metal plate (right side). Since the diameter is the same, the width could be the cause but since the coach as always had 295's, I can't say for sure. No tire deposits or dust, just a slight polishing and only very occasionally with the coach turning off the main road to a lower side road or while we are a going off road with it.

To me, it's not a potential wear point, can't cut a tire, etc so I just ignore it.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Tire size

Reply #10 –
Should only require a very small adjustment to cut angle (external screws on Sheppard M100 steering box) and also the physical stops on the steering knuckle.

Correctly adjusted, the physical stop is set so tire can NOT contact body or suspension components.

THEN, steering box is adjusted so there is a 1/8" gap at the physical stop. Lack of gap is the #1 reason for blown seals in the steering box, as line pressure can go sky high.

Yes, takes two people (one to turn the steering wheel), a small screwdriver and a crescent wrench.
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: Tire size

Reply #11 –
Pierce said in Reply #4:
"Bottom line is the 295's are slightly wider but for all practical purposes, the same diameter."
My question is "what is wider?"

I walked around comparing the tread width of 275 80 and 295 75 tires at truck stops and camp grounds using a tape measure.
As close as I could measure, the tread width of both size of tires measured 9.5 inches, even though the difference between 295mm and 275mm is 3/4 inch.

I do wonder if the cross sectional profile of the tires are different with the distance between sidewalls being wider on 295 tires, but have not heard of problems with side wall contact on duals.

A truck tire dealer told me that 295 75 and 275 80 are interchangeable because they are the same size.

I have seen car tires with the same size numbers on the side walls which are clearly different diameters.
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Tire size

Reply #13 –
The average 295/75 is 11.61" in width compared to 10.83" for a 275/80 so the width should be about 3/4" wider.

The lower aspect ratio should, all things being equal, allow for slightly better handling.

No, they don't come anywhere near touching in the back.

11.00R 22.5 is quite a bit taller and won't work with 295 or 275.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Tire size

Reply #14 –
Looking for info on dual tire spacing, I found these 11 pages to be quite informative.
 

Re: Tire size

Reply #15 –
Good info in easy to read form. I bookmarked it.

They left the reader a little in the dark on the increased risk of sidewall damage with the lower aspect tires. I think it's because the "bulge" is closer to the ground so more prone to damage from "road gators." Not a factor with 295/75 vs 275/80 as I see it.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)