Michelin X Line Energy Z or maybe Toyo M170

[richard5933]

I'm starting the search for new tires, hoping to get them installed in early spring. Right now we're running Firestone FS 400 in 315/80R22.5 size. We've been happy with them, and other than the tires being seven years old there is absolutely nothing wrong with them.

My initial thought was to replace them with a new set of the same. The tire dealer I'm hoping to work with is recommending Michelin, mainly I think because that is their main line and the Firestones will need to be ordered in.

So, I looked at the Michelin tires available, and with the FMCA discount they would end up costing about the same as the Firestones. Not sure if they are better, about the same, or a step down.

One tire I'm looking at is the Michelin X Line Energy Z. https://www.michelinrvtires.com/tires/selector/#!/info/x-line-energy-z-coach

Anyone have any experience with this tire? Since some of the larger Class A coaches out there are running the 315/80R22.5 size tires, I'm hoping that at least a few people can let me know what they think of these tires.

[wildebill308]

Have you looked at the Continental pricing?

I have been happy with my Continentals, I did save over $100.00 each over the Michelin pricing.

Bill

[richard5933]

28 minutes ago, WILDEBILL308 said:

Have you looked at the Continental pricing?

I have been happy with my Continentals, I did save over $100.00 each over the Michelin pricing.

Bill

I did look at them - the Conti Coach HA3 is a nice tire. There is one problem, and I'm not sure just how big a deal it is yet. With the drive train in our coach being what it is (8V71, 4-speed manual, and pretty lousy low-end power) I'm trying to stay as close as possible to the tire rpm (revolution per mile) set by GM of 495. Our current tires spin at 491 rpm, and the Michelin are the same. Every little bit lower than 495 serves to reduce low-end power, increase top speed, and of course mess up my speedometer. The Conti Coach HA3 only spins at 488 rpm, which would only serve to exacerbate the low-end problem and speedo inaccuracy.

[wolfe10]

Richard,

I would not make a decision based on less than a 1% difference in engine RPM/MPH-- very small difference in change to effective rear axle ratio.

[wildebill308]

The difference would be so small you couldn't tell. More like new tiers over worn and a change in air preshure.

Bill

 

[huffypuff]

5 hours ago, richard5933 said:

I'm starting the search for new tires, hoping to get them installed in early spring. Right now we're running Firestone FS 400 in 315/80R22.5 size. We've been happy with them, and other than the tires being seven years old there is absolutely nothing wrong with them.

My initial thought was to replace them with a new set of the same. The tire dealer I'm hoping to work with is recommending Michelin, mainly I think because that is their main line and the Firestones will need to be ordered in.

So, I looked at the Michelin tires available, and with the FMCA discount they would end up costing about the same as the Firestones. Not sure if they are better, about the same, or a step down.

One tire I'm looking at is the Michelin X Line Energy Z. https://www.michelinrvtires.com/tires/selector/#!/info/x-line-energy-z-coach

Anyone have any experience with this tire? Since some of the larger Class A coaches out there are running the 315/80R22.5 size tires, I'm hoping that at least a few people can let me know what they think of these tires.

I been running the Michelin XL Energy Z since 2014 and love them compare to the One years (Goodyear)  that was on the coach.   

[richard5933]

More research and now I've got more to consider. Apparently the OEM tire size on my coach is 12R22.5 and there are not that many good options for this tire size. Since the 315 present the possible danger of contacting the air bags when making tight turns, I'm leaning towards returning to the 12R22.5 tire size.

One of the tires I'm considering now is the Toyo M170. Anyone have experience with this tire?

[wildebill308]

7 hours ago, richard5933 said:

Since the 315 present the possible danger of contacting the air bags when making tight turns, I'm leaning towards returning to the 12R22.5 tire size.

Richard, Look at the 295/80R22.5 it is a little smaller than the 315 and according to this calculator spins at 491 rpm to the mile. It should help with clearance problems to.

https://tiresize.com/comparison/

Bill

[richard5933]

I've looked at the 295/80R22.5 tires in a number of brands. None of them are exactly at 495 rpm either, with most being about 500. I don't think that there is a really exact match for the tires that were on the coach from the factory. One thing that occurs to me is that the tread depth is much deeper on modern tires, and I think that this is what makes the rpm count off a little on modern 12R22.5 tires. Maybe I just need to have them shaved a touch to get them where they need to be.

The other thing that I've discovered is that there are adjustable stops on the front axle, and it should be very easy to adjust them so that the 315s on the coach now can't contact the air bags.

The Toyo M170 have been used on other coaches, and the results appear to be good. The size I need apparently come in two variants, the width being the difference. My guess is that the upper tire in this chart is the one that I'd want.

Tire Size	Load / Speed	MPH	Ply Rating	Load ID	Approved Rim Width Range (in.)	Tread Depth (1/32")	Product Code	Weight (lbs.)	Inflated Overall Diameter (in.)	Inflated Overall Width (in.)	Static Loaded Radius (in.)	Static Loaded Width (in.)	Max Load Single / Dual (lbs.)	Max Pressure Single / Dual (PSI)	Revs Per Mile
12R22.5	150/147L	75	16	H	8.25-9.00	19	546090	134	42.4	12.0	19.0	13.0	7390 / 6780	120 / 120	490
12R22.5	152/148L	75	16	H	8.25-9.00	19	546310	132	42.4	12.4	19.7	13.4	7390 / 6780	120 / 120	490

[wolfe10]

Richard,

Yes, if you have a Sheppard steering box, very easy external adjustments (to limit cut angle) with a small screwdriver.

[kaypsmith]

I have 4 12R 22.5 Toyo's on my coach now, 3 years old, no problems yet, and the ride is as good as any other that I have used in this coach.

[richard5933]

48 minutes ago, wolfe10 said:

Richard,

Yes, if you have a Sheppard steering box, very easy external adjustments (to limit cut angle) with a small screwdriver.

We've got factory power steering on our coach. The manual shows that there is a wheel stop adjustment screw on the steering knuckles, but it also appears to involve using a pressure gauge and changing a plunger setting on the power steering gear box. Seems like the primary setting is made with the plunger adjustments, and that the wheel stop screw is there for backup in case the primary adjustment is not working. Sure seems easier to just use the proper tires.

I've only had two occurrences that I'm aware of when the wheels were at the stops while rolling, both times when doing very close quarter maneuvers. Ideally, I'll be able to avoid this from happening, but of course it will be nice to have things adjusted as they should be to be certain there is never a catastrophic failure from the tire hitting and rupturing an air bag. 

[wolfe10]

This info for Sheppard steering box-- let us know what you have:

 

Yes, it is CRITICAL to adjust both the physical stops on the knuckles (adjust such that there IS clearance between tires and suspension/body components).

Then, (actually both done a little bit at a time) the plungers (tiny external screws) are adjusted such that there is a 1/8" gap between axle and stop.  This is really important, as if steering box is able to drive all the way to the physical stop, PSI in the steering sector goes way up and very easily blows the seals.

An easy job once you understand the concept and have a second person to turn the steering wheel stop to stop.

[richard5933]

43 minutes ago, wolfe10 said:

This info for Sheppard steering box-- let us know what you have:

Yes, it is CRITICAL to adjust both the physical stops on the knuckles (adjust such that there IS clearance between tires and suspension/body components).

Then, (actually both done a little bit at a time) the plungers (tiny external screws) are adjusted such that there is a 1/8" gap between axle and stop.  This is really important, as if steering box is able to drive all the way to the physical stop, PSI in the steering sector goes way up and very easily blows the seals.

An easy job once you understand the concept and have a second person to turn the steering wheel stop to stop.

This can be done without hooking up a pressure gauge?

And to correct what I wrote earlier - I'm not currently able to hit the stops when turning. What I'm referring to is the tires being able to slightly rub on the outside of the air bag when the steering wheel is turned to the extreme. Different, but probably equally bad. While my current tires have a little life in them, I'm seriously leaning towards swapping them all for the Toyo 12R22.5 at the start of the spring driving season. This would hopefully eliminate the problem with the 315s rubbing the air bags on a hard turn, since they are about 1/2" narrower than the 315s.

Guess GM put the 12R22.5 tires on there for a reason. My suspicion is that the previous owner put on the 315s because that was what he had on hand. He ran a fleet of commercial buses, and I'm sure that he just had his guys install what they had on hand and didn't even look closely at the specs. Besides, I think that most people assume that the 315s are the modern equivalent to the 12R22.5 size, but apparently not in every way.

[wolfe10]

Again, without knowing what steering box you have, this is only a guess based on the Sheppard (very popular HD steering box:

The mechanical stops absolutely should be set so that tires can not interfere with suspension or body.

Then steering box plungers screwed in until a small (1/8") gap.

Since your cut angle is enough for the tires to touch the bags, both mechanical stop and steering box need to be adjusted for slightly less cut angle.  Left side/right side can be very different depending on drag link, etc.

[richard5933]

Thanks. I'll have to add this to my list for the first service call after winter. Of course, I'll have to decide what to do with the tires before that, as the adjustment may not be necessary if I switch to the 12R22.5 tires.

I've got the books for the bus, and I'm sure that the tech at the shop also has experience with this. Between all that I'm hoping we can get this sorted out.