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old golfer guy · 07-02-2018, 10:19 AM

What problems might I incur with wrong dia. tires? Bought a 2013 Canyon Star 3856 on the F53 26000lb chassis. Dealer said they put new tires on. When I got home , Calif. I realized the tires were 255/70/22.5 instead of 255/80/22.5
Other than gas mileage and speedo off by 5 mph. what else can happen?
Concerned about shift points being off and not getting max torque going up hills.
Thanks

Skip426 · 07-02-2018, 10:35 AM

From your other post , I recall you saying the tires were 1" lower profile .
If the load rating of the replacement tires is the same or better, than OEM size: then the lower profile will actually help hill performance.
Just like changing the differential gearing from , e.g. 3:90 to a 4:10, engine RPM a little higher but the load on the engine/ trans is actually reduced.
You need to look at the two sizes of tires , circumference difference, to get the actual % , but the 65 mph indicated vs the 60 mph actual speed would put the difference at 9.5%.

Tireman9 · 07-02-2018, 11:44 AM

Quote:

Originally Posted by old golfer guy

What problems might I incur with wrong dia. tires? Bought a 2013 Canyon Star 3856 on the F53 26000lb chassis. Dealer said they put new tires on. When I got home , Calif. I realized the tires were 255/70/22.5 instead of 255/80/22.5
Other than gas mileage and speedo off by 5 mph. what else can happen?
Concerned about shift points being off and not getting max torque going up hills.
Thanks

You are lucky. While there is an OD difference the two sizes have a very unusual identical laod capacity for LR-g (110 psi) .When I first read your post I was concerned that the smaller tire would have a lower load capacity and there might be a possible overload.

But for some reason (probably a request from a tire manufacturer who already made one of the sizes in another country, probably in Europe) and didn't want to have to change the tire to sell in the USA.

Others will respond to the mpg and speedo question.

old golfer guy · 07-02-2018, 07:11 PM

I know the smaller dia. tires will make the engine add revs to get to the same speed as the larger tires. I can live ( if I have to ) with subtracting 5 mph form the speedo I see to get a decent reading of mph. What I am concerned about is does this alter the shift points on the tranny? Do I still get the right torque and down shifts when needed going up hills? I called 5 Star Tune today and they said the program would adjust for the tires and bring the shifting points back to where they should be and adjust the speedo too. My local shop, a speedo shop in Sacramento and the Ford Fleet service manger said nothing could be done about the speedo. Can 5 S. T. make that adjustment? If so I am going to try and get the dealer in Florida pay for it , they put in the cheaper tires.
Any more thoughts ?
Thanks

Soppy · 07-02-2018, 07:49 PM

One advantage , you will have more power climbing hills and the transmission will not hunt as much.

Sherpa Vern · 07-03-2018, 01:51 PM

Quote:

Originally Posted by old golfer guy

I know the smaller dia. tires will make the engine add revs to get to the same speed as the larger tires. I can live ( if I have to ) with subtracting 5 mph form the speedo I see to get a decent reading of mph. What I am concerned about is does this alter the shift points on the tranny? Do I still get the right torque and down shifts when needed going up hills? I called 5 Star Tune today and they said the program would adjust for the tires and bring the shifting points back to where they should be and adjust the speedo too. My local shop, a speedo shop in Sacramento and the Ford Fleet service manger said nothing could be done about the speedo. Can 5 S. T. make that adjustment? If so I am going to try and get the dealer in Florida pay for it , they put in the cheaper tires.
Any more thoughts ?
Thanks

Yes, there always seem to be a few more thoughts.

A bit more research on the Ford chassis revealed that the tire, 36.56" tall, installed by the dealer on your 26K chassis, is smaller than the 235 80 22.5, 37.3" tall tire that is standard for the Ford 20K chassis. To me, if that difference were not significant to the Ford engineers, they would not have increased the size tire on the 24K and 26K chassis. Larger tires are typically used to improve handling, performance, ride and perhaps safety margin beyond just weight capability. A one inch shorter sidewall and two inch shorter tire is certainly going to handle rough road, expansion joints and pot holes differently that the original tire.

The tire industry recognizes the 265 75 22.5 as the near identical sized replacement for the Michelin 255 80 22.5 . It is unfortunate that the dealer's mistake has tainted an otherwise exciting purchase and caused you a lot of effort, frustration and being "bugged" by the results of their behavior.

You make good points about shift points, torque and downshifts, all of which seem way more important than the speedometer error that seems to have taken the focus in this post and the post in the General Discussion forum, rather than the mechanical differences and potential safety issues that are involved by having a substantially wrong sized tire installed. All of the attempts to redesign the electronics to accommodate a simple mistake on the part of the dealer continues to seem like the most complicated and least productive way to resolve the obvious and easily identified cause of your concerns.

I think your idea to approach the dealer to cover the cost of the fix is a good one, but it should be focused on the installation of the wrong tires and covering those costs of getting the correct size installed. That is the thing that can be documented that they did wrong and will resolve all of the issues that have been discussed and caused by the wrong size tire. Asking them to reimburse for ECM changes, aftermarket tunes, etc, will likely not be well received.

Focusing on what they did wrong will be hard to deny. Challenge them to make this right and they will demonstrate if they are worthy of all of the praise that you received when you made inquiry as to whether or not they were a good dealer.

old golfer guy · 07-03-2018, 07:29 PM

Sherpa Vern, would you make the call representing me??? I'll gladly buy your a dinner at a fast food drive up window!!!
Dale

aether_one · 07-03-2018, 07:41 PM

Not enough difference to spend one more minute of concern on.

Sherpa Vern · 07-03-2018, 08:40 PM

Quote:

Originally Posted by old golfer guy

Sherpa Vern, would you make the call representing me??? I'll gladly buy your a dinner at a fast food drive up window!!!
Dale

I wouldn't mind talking to you by phone about this issue and why I feel the way I do, but I'm guessing that the dealer can be convinced that it would be in their best interest to handle getting you back to having the correct tires. Admit the mistake and move on would be my advise to them.

When I get back to Cameron Park, I would be happy to buy breakfast for you at the Train Station. I have breakfast there every day when I'm in that area, February through May and other random times of the year.

We could probably talk about lots of things, but I think you already know my feelings on the tire issue. I just hope that you find a simple resolution that makes you happy.

old golfer guy · 07-05-2018, 06:05 PM

Thanks for all the input. Called the Independence rv sales manger this morning, told him the problem. He said it was his mistake and go to a local tire shop, see if they will buy the used ones and put on the right size tire!! Then send the bill to him. Will do that next week.
Alls good in the neighbor hood.
Dale

Sherpa Vern · 07-06-2018, 12:13 AM

Nice job!

Independence RV apparently has earned their good reputation and know how to keep good recommendations coming based on your result.

gruelens · 07-06-2018, 12:49 AM

Quote:

Originally Posted by old golfer guy

What problems might I incur with wrong dia. tires? Bought a 2013 Canyon Star 3856 on the F53 26000lb chassis. Dealer said they put new tires on. When I got home , Calif. I realized the tires were 255/70/22.5 instead of 255/80/22.5
Other than gas mileage and speedo off by 5 mph. what else can happen?
Concerned about shift points being off and not getting max torque going up hills.
Thanks

The link below will provide a Tire Size Calculator. You can then see the exact differences the two tire sizes make.

https://www.tacomaworld.com