[Archived]

Bill, in the absence of the 120 tires that came on the coach originally folks are using 315 tires. I have not heard of any issues with them.

[Archived]

My dealer here outside of Hanover, PA said that he can get both. The 315’s are about $120 per tire more. I’m not really worried about the the cost if it is a better/safer tire.

[Archived]

That being the case I would go with the 120. The 315 has about 9000 # capacity, the 120 around 7400 (going by memory) but you don’t really need the extra capacity. I think the pressures will be lower with the 315 but as I recall I ran my tags around 70 PSI on my 87 coach and I don’t think Michelin even lists 315 pressures that low.

Just make sure the 120 are comparable to the XZA in terms of speed rating and application.

[Jerry]

Doesn’t the XLA require a 9 inch wide rim to take full advantage of the tire ? the 12R will probably the weight his wheels are rated for

good luck

[Bill]

we went to 315’s on our coach. Michelin a few years ago made a completely separate psi air chart for 315 tires mounted on 8.25 inch wide wheels. After all, later XL ones and current XL two models have 8.25 inch inner dual steel drive wheels. As long as duals sidewalls don’t touch during flection, your fine. We did it because weight/psi is a bit lower for 315s on 8.25 in wheels, vs psi needed for same weight carrying on 12Rs, making for a slightly smoother ride. Be sure to check the stamped carrying cap and Max air pressure stamped on your outer dual since it’s easy to see if you wheels have a high enough rating for 315. Our 1992 wheels were able to run 315s.

[Don]

We put 315’s on the steer and tag but were adviced against installing them on the drive as the spacing would cause the tires to rub periodically and even when they were not they would be so close the heat would not disipate properly and could lead to premature failure.

When it was time for all new tires we installed 8 12R 22.5’s Michelins 3 years ago and we now have the best ride of any set or combination of tires since purchase.

[Dean]

8.25 inner and 90 outer is the standard wheels. I did have 90’s on both inner and outer duals with no issues. The only problem was the outside space at the fiberglass fender was reaalllly close.

[Archived]

I
personally like the higher load rating of the 315’s. To me I would rather spend
the extra $’s in the beginning for the peace of mind. I realize they may not be
necessary, but I would like to try them if they will work and if there is no
strong downside.

So money aside what would you do?????

Bill III

[Bill]

One has to ask is it worth 800 bucks extra for tires that exceed the weight limits of the axles ,wheels and GVW of the bus JMO

good luck

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2005 XL Thompson Coach

Rarely tow anything behind us.

Sold: 1993 Liberty that we loved for 12 years.

[Archived]

Maybe
I am over thinking this, but I certainly would have paid $800 not to have a
blowout on I95. Was it my fault to be driving on what looked to be perfect 8
y/o Michelins that have always been stored indoors and had less the 10,000
miles on them, maybe so? I was using a TPMS with both psi and temp, both of
which were fine and gave no warning at all. Funny thing is it cost me $750 to
have a Goodyear G159 installed roadside to get me back on the road. This is a
tire that I will not use again so pretty much was a waste of money.

Honestly I am not trying to overspend. I am just trying to weigh out my
options. I come from an automotive racing background and I learned a long
time ago that a little extra cost upfront may cost you less in equipment and
healthcare in the future.

[Dale]

We have often preached about tire age and not tread depth being the criteria for replacement.

What makes that even more important is if you are not the original owner of the tires you don’t know if the tire has been damaged by underinflation. The size and capacity of the tire does not appear to make a tire safer or last longer. There have been a number of reported failures of 365 tires on the tag for example and those tires at that location probably are rated for as much as twice the load they carry. We can only presume the tires that fail prematurely at some point were run underinflated at some point in their life..

When the amount of damage a blowout can cause is considered what makes sense to me is to pull off perfectly good tires that are 6 years of age and replace them.

[Bill]

My rig a 1991XL had Michelins 315’s all around when I bought it. I started to replace them and based on conversion with NWBusNuts members they said that the Michelins showed surface cracking faster than other brands. So I turned to Les Schwab and bought 315’s for the front. My next new tires were again 315’s and I put them on the front and moved the first set of 315’s to the tags. I later bought all new drives and went with four 12’s based on price. I b ought Toyo’s and my only complaint with then would be the smell, they do have a funny smell that doesn’t go away.

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2005 XL Thompson Coach

Rarely tow anything behind us.

Sold: 1993 Liberty that we loved for 12 years.

[Bill]

Thanks
guys I really appreciate all of the input. I still have not made a final decision.
From what I gather at this point 315’s will fit, but may not really improve the
coach or make it safer in any way.

Jon, what you say makes perfect sense. Other than the exceptional visual
condition of the tires and the coach, I do not know exactly how the
tires have been treated. I was running my Audi race car last Fall at
Summit Point in WV and blew a brand new Hoosier (considered one of the best and
expensive race tire) also on the right front, at over 160mph. Again, no real
reason or any indication that it was going to happen.

I realize that none of this is a perfect science. I just want to be as
educated on the safety aspects of these coaches as possible. I have done about
10,000 miles a year for the past 5 (1987 Newell and now the Liberty) and I plan
to do more than that as the years move forward.

I really do appreciate the knowledge of those that have been there before me.
Thanks

[Archived]

CarlisleBill,

All tire manufacturers make it clear that if a tire is run at a pressure 20% or more less than the inflation pressure required for the weight carried the tire has been damaged beyond repair.

The resulting failure is typically a “zipper” failure in which the entire side opens at once. It is a catastrophic failure due to the sudden and complete loss of the belts in the sidewall. A Prevost owner had that type failure as he was airing up an inside dual tire. The fact it was inside probably saved his life because it failed so suddenly he suffered hearing loss and the fender on the coach was blown off.

The damage from running underinflated is visible it someone wants to take the time to dismount the tire. The inner liner of the tire will show the damage in the form of a shredding or a distinct line around the circumference of the sidewalls probably from the extreme flexing due to underinflation.

As a confirmed chicken I would prefer to just err on the side of caution and replace tires that might be able to give me additional years of service. That cost is pretty cheap when I consider the cost per year compared to all other costs of ownership. If I factor in the potential damage and cost of a roadside replacement tire replacement to a six year schedule seems cheap.

[Don]

The 12R tires are 20 lbs lighter ea and a few rpm per mile better than the 315 I was told by the Michelin man but I never checked to be sure