Changing Tire Sizes, Pros vs. Cons

[jleamont]

I am considering changing my tire size since it is a hard one to locate and my space is limited to carry a spare (maybe under the bed). So here is what I have, axle specs (weight ratings). My steer tires are 15 months old, drives are 3 years old and are the incorrect size.

Coach OEM size; 295/80R22.5 (I only have these on the steer, drive tires are a 295/75R22.5 truck tire Firestone FS560)

Front axle weight rating; 13300lbs

Rear axle weight rating; 23000lbs

Here are my considerations;

315/80R22.5 concerns; width could cause tire kissing on the duals (.7" wider than the 295/80) ,overall weight of the tire is 13.3 lbs each heavier which results in more rotational mass that will decrease fuel economy.

11R22.5 (16 PLY) concerns; .6" (wider than my drives now) narrower tread pattern, air pressures table lower (not sure if this matters). Pro's, lighter, easily accessible, in my weight range same height as my steers.

My plan was to replace the drive tires next season, for nothing more than the coach sits funny with a short tire on the rear and tall on the front and run the steers for another two-three years and replace them so all 6 match.

Any reason why I shouldn't do this? I was considering the 11R 16 ply.

 

 

[wayne77590]

Joe, here is a Tire Size Calculator that may assist you.

I went from Michelin to TOYO's.

[wildebill308]

17 hours ago, jleamont said:

I am considering changing my tire size since it is a hard one to locate and my space is limited to carry a spare (maybe under the bed). So here is what I have, axle specs (weight ratings). My steer tires are 15 months old, drives are 3 years old and are the incorrect size.

Coach OEM size; 295/80R22.5 (I only have these on the steer, drive tires are a 295/75R22.5 truck tire Firestone FS560)

Front axle weight rating; 13300lbs

Rear axle weight rating; 23000lbs

Here are my considerations;

315/80R22.5 concerns; width could cause tire kissing on the duals (.7" wider than the 295/80) ,overall weight of the tire is 13.3 lbs each heavier which results in more rotational mass that will decrease fuel economy.

11R22.5 (16 PLY) concerns; .6" (wider than my drives now) narrower tread pattern, air pressures table lower (not sure if this matters). Pro's, lighter, easily accessible, in my weight range same height as my steers.

My plan was to replace the drive tires next season, for nothing more than the coach sits funny with a short tire on the rear and tall on the front and run the steers for another two-three years and replace them so all 6 match.

Any reason why I shouldn't do this? I was considering the 11R 16 ply.

 

 

 

I don't see any reason you can't. For your own peace of mind I would measure the gap between the rear tires( at the bottom) I bet you have plenty of room.

I don't think the more rotational mass will be a problem. I think the larger rolling diameter will help mileage.

Bill

 

[five]

Some general comments, Joe:

-  Why not leave the 295s on the front?  My last coach had a 14.6k front axle and plenty of reserve carrying capacity with 295s.  However, as you noted, they are hard to find.  We had a RF blowout last year and sat on I 55, south of Chicago for five and a half hours while GS Road Service found one.  But at 15 months old, they are virtually new.  This coach has a 17k front axle and 315s.

-  The feds just recently gave approval for increasing the rear axle GW above 20k...are you sure yours is 23k?  I like to do things the easy way, so if you want to change the rears, I'd put on 295s.  Then you are back to all OEM, no adustments for speed, mpg, trans shift points, etc.  As noted above, the biggest disadvantage is finding one if you have a failure.

[jleamont]

Five, thank you for the recommendations. My weight rating is 23,000, most states do not allow that much on an axle although times are changing. I have always spec'd trucks with a 23,000 rear but we registered them lower, they held up better under abusive situations. 

[rsbilledwards]

J,

Be sure the speed rating is a J and not an L 75VRS  65 MPH

[tireman9]

It would help if we knew your measured "4 corner" tire loads or at least the individual axle loads. To work with just the rating the best you can get are a bunch of guesses.

Some other numbers you need to consider when consulting specifications on possible tires:

Max load capability at max inflation for each Load Range you are considering.

Minimum rim width and the width of the wheels you have. (spec not what you measure with a tape)

"Minimum dual spacing"

You mentioned carrying a spare. You might watch this short video.

Have you confirmed that you have space for a spare tire only?

[jleamont]

Roger, I watched the video, walked out to the coach with a tape measure and was pleasantly surprised to see my basement doors are 47" wide. So I can actually fit one under the coach. My size is common among over the road busses but not common amongst tire dealers for some odd reason. Size; 295/80R22.5

I guess next year I will order up the proper size. 

I have two matching aluminum wheels that I have not installed on the inner duals yet (inner duals are steel now). I think what I'm going to do is replace the incorrect size drive tires next year swing those aluminum inner wheels on at that time and either purchase a 5th tire new for a spare at that time or see if the tire dealer has a decent used one to toss in the basement. I will mount them myself, I have all the required tools to do so, my blue cobra hasn't seen much action in a few years since I sold the mobile truck repair business.

 

P.S. Love your website, I have sent several people from social media to it for advice. That is a great tool!

Thank you

Joe

[hermanmullins]

Nice video, I kept one of the best take off as a spare. It does fit in my slide tray but it makes  the tray harder to pull out and it does add quite a bit of weight.

295-80R 22.5 is not a real popular size.

Herman 

[manholt]

Joe.  Just for giggles, have you checked with HR to see what the original tire size was in 02' ?

295's are hard to come by and I feel very fortunate that the dealer in Oregon was able to locate them in 14'.  Carry a spare in coach?  Not happening !  When I put my feeble brain in gear and remember all the flat tires I have had....way more front than rear and my  fronts are 315's.

Carl

[jleamont]

Carl, 295/80R22.5 is the original tire size. I prefer not to carry a spare. But I also don't want to sit for 5 hours on the side of the road. Time is money and them chasing a tire down can really add up. That's probably why the dealer put 295/75R22.5's on it, but they are the wrong load range.

[rsbilledwards]

J,

I feel the same way, but the loss of the basement stowage bugs me so I think I will make a cage tray for up top. I can just see Herman and Carl's brains whirling. How in the world is he going to get it top side, he is nuts. I can't imagine making the trek to Alaska next summer and not have a spare, just the tire is adequate. Havin a couple bars on the coach to change rubber is not difficult. A little sweat on the brow is healthy now and then. A simple cage out of aluminum and the tire up there piece of mind, looking or a 275 70 22.5 on the highway to Alaska a head ache. As for getting it up there I have a skidder and forks that will get it roof high. Getting it down, push it off and chase it down the highway.

[hermanmullins]

Bill, you are correct, spinning so fast the governor kicked in. I have a 295 in my large bay tray. In side the tire I stow power cords and water hose. In the center I put cleaning supplies, cases of water and whatever else will fit. I was surprised of how much space I still had. Just have to pack well.

Darn I'm still getting dizzy. Hold on Lizabeth this may be the big one.?

Herman 

[manholt]

 I can picture the tire heading down the Dawson Hwy!  Don't know about you, but I don't run well anymore...

As long as the tire and the cage is the same height as the rest of the stuff up there, you should have no problem.  I would also include a lid to keep the UV light and weather off the tire.  As far as getting the tire down, I would use a small block and tackle to slide it down the ladder...not the side of coach !

[wildebill308]

Has anyone had experience with the new tire program Coach Net is offering?

If it is as good as the road side assistance it may be a viable option.

Bill

[jleamont]

Bill, a rack on top of a DP. Hmmmm, when that tire drops hopefully it bounces away from your coach and not off of the side wall. 

Wildebill, I just renewed my Coachnet and didn't notice it, I will have to go back and re read the options. 

[wildebill308]

Hear is a link. https://coach-net.com/Products/Hazard-Protect 

Bill

[manholt]

Joe.  Re-read what I wrote.

Bill.  First I've heard about it.  Nation wide is, among other things, an Insurance Company, so I guess CN have rolled over to them !?  I have had CN since 09' when I gave up on Good Sam.

Carl

[rsbilledwards]

I visited the posted site and read it all and then I found this. It is always curious to me when they limit the coverage to in this case to "The current model year + 14 years" . What is the matter with those preceding years, drivers/ owners, tires. Am I missing something?

Bill Edwards

 

[manholt]

15 years on the same tires, to us, is ridiculous...but, to people that think cars, it's not...what the blank do I know?

[rsbilledwards]

Carl,

True, but in this case, it did not go anywhere. In this case the miles were put on it early and the wife developed MS I believe and could not stand to ride in it. The fact that it sat in a warehouse many years and only went some short distances when used and did not jeopardize anyone. If you were to have looked at the tires you would never guess. The coach only had 11,781 on it when I looked at/picked it up it in April and 113 hours on the Onan 7500. It was a Barn Find!!! I will offer more details when I get a blog going and that, is going to be a real Hoot.

To put you at ease the first thing I told the RV dealer was that it was not going to go to Colorado on that rubber which I had not seen. He told my boots on the ground he was not going to make a deal. When I called him, he had had a bit of time to think about it. When I said, meet me half way he said OK. I sent a bank check for the coach less the tires and batteries. He split the cost of the tires and allowed the batteries, all of them. The tire deal had already been made and paid for. I took the 3 year old batteries to the CARQUEST dealer and he warrantied the whole bunch. I sold the deep cycle little car/house batteries and kept the big chassis batteries to put in the Feather Lite trailer with the solar charging panel from the coach. I took the money from the little batteries and added some and bought Crown 260s for the coach.

The tires he kept, except for one that I made him give me as a spare. He was not happy about that, as he wanted to put them on another coach that had more checks in it than US Bank and Wells Fargo combined. I was only able to do that by virtue of the education I have received from all of you on this forum over the last several years.

Thank you all!!

Bill Edwards

[manholt]

 Good for you!  Glad we could save you some bucks....I really love Dealers...NOT !   "Barn Find?"  No kidding.

Your up early/or late!

[wildebill308]

Pictures?

Bill 

[rsbilledwards]

Bill,

Yes, soon enough, I have had it sitting in one spot with the basement torn apart repairing a sewer leak and as a result replacing all the carpet including the side walls. I can't leave things well enough alone so made countless improvements by organizing wiring, plumbing and the removal of 20 fee of PEX, I do not know how many feet of useless wire. This thing must have been built on a Monday after a hard weekend because everything is just chaos. I have moved the inverter, transfer switch, added a hard wired surge protector with a remote, moved the utility tank module board all to a serviceable location on the ceiling between the chassis rails. I re-plumbed the black water tank so as to prevent another freeze fracture and moved the basement heater to a less intrusive location off the cargo bay floor. Then the poor ole thing needs a bath before I can show it off,

I have scrubbed the roof white and have a bucket of Son Shield to lay down. It is an elastomeric roofing re-surfacer with the 3M ceramic ball insulation in it. It is supposed to be very good and then I can install the solar system and hit the road. The rest I will do in Arizona this winter hoping it is warmer than last year.

Thank you for the interest!

Bill Edwards

[manholt]

Why don't you build a new coach, while your at it?

By the time you get finished, re sale will be "0", since your the only one who knows how to run it !

Carl