Drive Tires - 23,000 # Axle & 295/75R22.5 questions vs OEM’s being Different

[richmelcole@sbcglobal.net]

HI All,

It is time to replace all four drive tires.  The old tires are 295/75R22.5 Yokohama 104ZR.  I was looking at the Hankook AL21 load range "G" tires.  The rear axle GAWR is 36,000 lbs. on my Windsor and the tire is rated at 5,675 lbs. each.  This seems strange that an over the road truck tire wouldn't handle the weight of my coach.  Is there something I'm missing to purchase the correct tire?  Any help would be appreciated.

Richard

[tmw188]

I would look at that axle weight rating that is incorrect. Maybe more like 23,000 lbs. Outside of that I would look for H rated tires. 

Edited March 18, 2023 by tmw188

[vito.a]

Yes, 36,000 pounds is not correct.  A 40" 200 Windsor has a 23,000-pound rear axle.  38' and shorter has a 20,000-pound rear axle.  

Maybe you confused it with the GVW which is 36,000 pounds. 

[Tom Cherry]

12 minutes ago, vito.a said:

Yes, 36,000 pounds is not correct.  A 40" 200 Windsor has a 23,000-pound rear axle.  38' and shorter has a 20,000-pound rear axle.  

Maybe you confused it with the GVW which is 36,000 pounds. 

Yes, the rear axle on the .longer Roadmaster (40 ft) were rated at 23,000.  The GVW includes the front.  You need, probably, Load Range H tires.  My 295/80’s are rated at 5,750 Pounds or a smidge more at 100 Psi.  I would think that your 295/75 would be in that range at 105 - 110 PSI.

Look at the original inflation placard on the drivers lower console vertical wall or maybe in the cabinet.  Your owners manual may also have the values to achieve the 23,000 rated capacity.

[trailmug]

If I recall correctly, G tires would work with the rear end of our 45' sig.. I tried to source some Toyo M122s for the rear, but couldn't find them locally. Put the M144 H steer tires all around as our local tire dealer stocked them 4 at a time. Very happy with them, as others seem to be. 5 years (outside covered storage), no checking, stay perfectly inflated over winter.

My understanding is you can also use 11R22.5 truck tires in place of 295/75/22.5.

Edited March 18, 2023 by trailmug

[richmelcole@sbcglobal.net]

I wanted to update my post.  Tom was right about axle weights.  Took a picture of the placard behind the drivers seat.  Front axle - 13,000 lbs. /Rear axle - 23,000 lbs.  Top placard lists 295/80R22.5 for front and rear tires.  The bottom placard lists 205/80R22.5 tires front and rear.  My new front tires are 75R but the placard recommends 80R.  It that OK?  All drive tires I have found have a max load of 5,675 lbs.  Will 75 lbs make a difference or should I find a different tire that will work with my new fronts.

Thanks,

Richard

[RedSectorA]

10 minutes ago, richmelcole@sbcglobal.net said:

I wanted to update my post.  Tom was right about axle weights.  Took a picture of the placard behind the drivers seat.  Front axle - 13,000 lbs. /Rear axle - 23,000 lbs.  Top placard lists 295/80R22.5 for front and rear tires.  The bottom placard lists 205/80R22.5 tires front and rear.  My new front tires are 75R but the placard recommends 80R.  It that OK?  All drive tires I have found have a max load of 5,675 lbs.  Will 75 lbs make a difference or should I find a different tire that will work with my new fronts.

Thanks,

Richard

Look for an 16 H rated tire, 16 ply and H load rated for your 13k front axle. Your minimum load index is 6,500 per tire.  I know Toyo has 295 80 r22.5 H rated tires. Don't know much about 205 80 size.

 

[Tom Cherry]

17 minutes ago, richmelcole@sbcglobal.net said:

I wanted to update my post.  Tom was right about axle weights.  Took a picture of the placard behind the drivers seat.  Front axle - 13,000 lbs. /Rear axle - 23,000 lbs.  Top placard lists 295/80R22.5 for front and rear tires.  The bottom placard lists 205/80R22.5 tires front and rear.  My new front tires are 75R but the placard recommends 80R.  It that OK?  All drive tires I have found have a max load of 5,675 lbs.  Will 75 lbs make a difference or should I find a different tire that will work with my new fronts.

Thanks,

Richard

Sadly, it is always best to go back to the OEM tires.  The 295/80 LR “H” were used to run the lowest (ride comfort) pressures while having the capacity to carry the rating of the axle.  Monaco’s not the most forgiving on “excess” capacity….at least on mine. IF I understand correctly, you have 75’s on the front.  What I would do is load up the rig and get my passenger(s) in and find a truck scale (with a full fuel tank and “presumably” a full fresh tank….but if you never go out with a full tank….then use 2/3) and weigh each corner.  The protocol is easy.  Find a scale that is flat with only one or no guard rail.  Put the MH on the scale and get total front and rear weights.  Then drive on the scale with only one side (wheels) on the scale….split front to rear as before.  Get that weight.  Subtract each individual weight from the original total.  NOW…You have corner as well as total axle weights.

I have NO idea what that we’ll be, but you can look at your front axle.  Unfortunately mine is front heavy….and I don’t have much margin.  Thus I have to run the recommended 115 PSI or near it up front.  Now look at your front tires.  Look up the load capacity.  Look at the Max pressure stamped on the rims.  I have run 120 PSI on the OEM Goodyears, but, the tire engineers told me that really just increased the potential for a blowout as well as overheating the tires.  If you can safely run 115 up front or lower and get the weight capacity needed for your max loading, then leave them up front.  BUT….GO BACK TO THE 80 series next time.

Personally, I would NOT put the 75’s on the rear.  Put on the 80’s.  The Toyo is a popular tire and i know that many run other brands, but the folks I communicate with offline are running the Toyo, as I have all 6 Toyo on mine. 
 

IF YOU CANNOT GET THE RATED CAPACITY AT 115 or less up front, then, try reloading or dropping back on how full you fuel or maxing out the water tank.  I rarely have a full tank and if boondocking, I fill it a few miles out.

That’s my take….

[96 EVO]

1 hour ago, richmelcole@sbcglobal.net said:

  Top placard lists 295/80R22.5 for front and rear tires.  The bottom placard lists 205/80R22.5 tires front and rear.   

That's odd!

Big weight carrying difference between a 295 & 205 tire!

[Tom Cherry]

1 hour ago, 96 EVO said:

That's odd!

Big weight carrying difference between a 295 & 205 tire!

GOOD CATCH !  That has to be a MISPRINT.  I did some research using your original Sales Brochure and axle Ratings and also pulled your owners manual.

MY CONCLUSION (others might differ but the math is simple), the OEM’s, from the Sales Brochure, were 295/80.  There AINT no 205 Listed in the tire charts in your manual.  Here is the math.  Assuming you are not overloaded….and don’t know your corner weights, then with the 295/75 on the front, you  need 120 PSI in the FRONT to achieve or equal the Front Axle capacity.  IF you had 295/80, that would be 100 PSI.  THIS ALSO ASSUMES THE 295/75 are Load Range H.  

So, looking at it logically, assuming I’m you have the 295/75 LR H…..up front….  REPLACE THEM with 295/80 LR H. Move the front to the rear.  If there is almost NO WEAR, the rule of thumb is maybe 4 /32 or less….then pair them up with two brothers….same brand and model.  They will be fine back there.  I have been told to keep both on one side or also put them on the outside as the heat from the axle will bump them up 3 PSI.  Myself and others here have confirmed that if both are set to 100 PSI, After the heat up for an hour, the inside, per our TPMS, will be 3 PSI higher than the outside.  Let the newer ones run on the inside.

That would be my solution.  Now if they are LR G, then read the tables and make sure they are inflated to achieve 5,750 Pounds.

The above is what many people do anyway…..but in your case, your ride will suffer and I Think you are at a higher risk of steer tire failure from the 120 PSI vs the 100 PSI for the correct tire….

YOUR CALL….MY MATH…

[richmelcole@sbcglobal.net]

Thats alot to digest Tom.  One thought I had, since my fronts (75R) are 16 ply, rated at 7,160 lbs each, they would cover the front axle weight.  Could I use the same steer tire for the rear which is rated 6,610 lbs. each without causing any problems with wearing?

Richard

[trailmug]

As long as the tire is carrying at or under its single/dual rated load, I'd use the inflation pressure table from the tire manufacturer for the load range / size you have and run it. Our sig runs 120PSI up front cold, which goes to 140+ in summertime mountain runs! Michelin wanted 115 for the same size / load range. The 75 vs 80 will make a small difference in the revs-per-mile, so adjust your mileage/speed expectation/computation.

Edited March 22, 2023 by trailmug