Aspire tire size change

[edgray]

After reading all the recent threads about problems with the OE 295/80R-22.5 GY 670RV steering axle tires, I'm trying to determine IF Entegra changed anything on the chassis, or in the size of the coach wheel well, or the rim width, when they went to the 315 size tires. I think they made the change effective with the 2017 model year, but continued with the same GY tire brand. I understand they went with Michelin 315 on the 2018 coaches.

In simplest terms, my question is: "Can I simply put 315/80R-22.5 size tires, which are load range "L", on my 2016 Aspire without changing anything else?"
I'll appreciate your replies, and offer my thanks in advance. Anybody?

[Chargerman]

The 315 requires a wider wheel. I believe 1 inch wider. You can check the Michelin spec sheet to confirm

[Gary.Jones]

Not the answer you want..... but why would you not replace your Goodyears with 295 Michelins?

Gary

[Jose67]

I am replacing my steer axle tires to Michelin X Coach HL Z 295/80R22.5 Load range: H, Part number: 31078, Wheel size: 8.25", Load rating single tire 8,270 Lbs, Pressure: 123 PSI.

The 2015 has a solid steer axle rated to 16,000 lbs by the axle manufacturer and de-rated by Spartan to 15,860 Lbs. The GY tires are rated for 7,930 Lbs each.

With that said, these tires will give us a 4% greater safety margin. Not much but it all counts. Specially, when it comes to life safety.

My GY's are dated 2014, Week 18.

[FreshAir]

Originally Posted by edgray

After reading all the recent threads about problems with the OE 295/80R-22.5 GY 670RV steering axle tires, I'm trying to determine IF Entegra changed anything on the chassis, or in the size of the coach wheel well, or the rim width, when they went to the 315 size tires. I think they made the change effective with the 2017 model year, but continued with the same GY tire brand. I understand they went with Michelin 315 on the 2018 coaches.

In simplest terms, my question is: "Can I simply put 315/80R-22.5 size tires, which are load range "L", on my 2016 Aspire without changing anything else?"
I'll appreciate your replies, and offer my thanks in advance. Anybody?

I would say no on changing to a 315 w/o going to a 9" rim width from our current 8 1/4" Aspire ones..

As far as wheel well size or other coach differences I can't say. As for tire size I had the same question and this is what I came up with.

The GY 295/80/22.5 preferred rim width is 8 1/4" but will be fine on a 9" rim.

The Michelin 315/80/22.5 requires a 9" minimum rim. or a 9 3/4"

Our rear rims are 8 1/4" so I am assuming our GY 295's fronts are on the 8 1/4" rim. but not sure as I can't find a size stamped on them. Regardless of the tire Brand they all adhere to the same specs. 295's require minimum 8 1/4" width, 315's require 9" minimum width rims, etc.

It would be nice to step up a bit from our LR H's to an L but no use exceeding the axle limit by much.

I'm leaning on going with the 295 "X Coach HLZ's" which Michelin say are in back order status.

[Marcosdad]

Ancient history, but when my tires were changed to 315s on our '13 Aspire, the wheels were changed to 9". This was done as a recall. Note, that our Aspire had IFS. We never had a problem with the wheel well rubbing and never dumped the air unless the wheels were straight.

[Steve Ownby]

Originally Posted by FreshAir

I would say no on changing to a 315 w/o going to a 9" rim width from our current 8 1/4" Aspire ones..



As far as wheel well size or other coach differences I can't say. As for tire size I had the same question and this is what I came up with.



The GY 295/80/22.5 preferred rim width is 8 1/4" but will be fine on a 9" rim.



The Michelin 315/80/22.5 requires a 9" minimum rim. or a 9 3/4"



Our rear rims are 8 1/4" so I am assuming our GY 295's fronts are on the 8 1/4" rim. but not sure as I can't find a size stamped on them. Regardless of the tire Brand they all adhere to the same specs. 295's require minimum 8 1/4" width, 315's require 9" minimum width rims, etc.



It would be nice to step up a bit from our LR H's to an L but no use exceeding the axle limit by much.



I'm leaning on going with the 295 "X Coach HLZ's" which Michelin say are in back order status.

Michelin allows 315s on 8.25" wheels and publish an inflation chart addressing that combo. Continental allows that combo also.

[Jose67]

Originally Posted by FreshAir

I would say no on changing to a 315 w/o going to a 9" rim width from our current 8 1/4" Aspire ones..

As far as wheel well size or other coach differences I can't say. As for tire size I had the same question and this is what I came up with.

The GY 295/80/22.5 preferred rim width is 8 1/4" but will be fine on a 9" rim.

The Michelin 315/80/22.5 requires a 9" minimum rim. or a 9 3/4"

Our rear rims are 8 1/4" so I am assuming our GY 295's fronts are on the 8 1/4" rim. but not sure as I can't find a size stamped on them. Regardless of the tire Brand they all adhere to the same specs. 295's require minimum 8 1/4" width, 315's require 9" minimum width rims, etc.

It would be nice to step up a bit from our LR H's to an L but no use exceeding the axle limit by much.

I'm leaning on going with the 295 "X Coach HLZ's" which Michelin say are in back order status.

I ordered mine and it took 1 1/2 weeks to get them. Not too long. I added the Balance Masters also.

[Jolar01]

I have also been looking to upgrade the steer axle tires on our 2016 Aspire, due to the front end corner weight issue. We are currently running 125 psi in our steer tires, corner weights 7,480 # driver’s side and 7,700 # passenger’s side (weights without occupants) so when occupied we would be over maximum 7,830 # limit. If we upgrade to Michelin or Continental 295/80/22.5 tires we would mediate the Goodyear situation but gain nothing in safety margin. We can upgrade to 315/80/22.5 tires on the existing 8.25“ Alcoa rims, but would gain nothing in the area of safety margin as both Michelin and Continental derate the load carrying capacity to 7,830 # same as 295/80/22.5.
So looking at going to 9”Alcoa rims cost approx. $350 to $450 depending on the finish, however here is where the rub comes in. There is a clearance between the existing 8.25” rims and the steering arm on the Meritor fixed I beam axle of 7/8”. As best that I can determine the existing rims are standard and as such have an offset of 6.60” (offset is the distance from the back side of the rim where mounted to the hub to the centerline of wheel), the 9” rims have an offset of 6.94”. So, with the existing rims (8.25”) there is a distance from outside face of the front hub to the backside of the rim of (6.60” + 4.125”) or 10.725”. The 9“rims would be as follows (6.94” + 4.5”) or 11.44 “. Therefore, as previously stated, there was 7/8 (.875)” clearance between the existing rims and the steering arm; this would be reduced by (11.44” – 10.725”) or .715” leaving a clearance of (.875” - .715”) or .16” (5/32”) too damn little.
Possible solutions are two fold, one, my assumptions on the offsets of the 8.25” rims are incorrect or calculations are wrong. Possible solution—to have Big Mike at Spartan have someone take a 9“ rim and check clearance on a Mountain Master Chassis with Meritor front axle (2016 Aspire). Second solution—find a rim with less offset or add a filter plate to move the rim away from the hub by a ½“ or so. Both of these solutions would need to be approved by Spartan and Entegra.
So still looking for a clean solution, Help. I will forward this to PJ at Entegra and Big Mike for their insight.

[Chuck1957]

Originally Posted by Jolar01

I have also been looking to upgrade the steer axle tires on our 2016 Aspire, due to the front end corner weight issue. We are currently running 125 psi in our steer tires, corner weights 7,480 # driver’s side and 7,700 # passenger’s side (weights without occupants) so when occupied we would be over maximum 7,830 # limit. If we upgrade to Michelin or Continental 295/80/22.5 tires we would mediate the Goodyear situation but gain nothing in safety margin. We can upgrade to 315/80/22.5 tires on the existing 8.25“ Alcoa rims, but would gain nothing in the area of safety margin as both Michelin and Continental derate the load carrying capacity to 7,830 # same as 295/80/22.5.
So looking at going to 9”Alcoa rims cost approx. $350 to $450 depending on the finish, however here is where the rub comes in. There is a clearance between the existing 8.25” rims and the steering arm on the Meritor fixed I beam axle of 7/8”. As best that I can determine the existing rims are standard and as such have an offset of 6.60” (offset is the distance from the back side of the rim where mounted to the hub to the centerline of wheel), the 9” rims have an offset of 6.94”. So, with the existing rims (8.25”) there is a distance from outside face of the front hub to the backside of the rim of (6.60” + 4.125”) or 10.725”. The 9“rims would be as follows (6.94” + 4.5”) or 11.44 “. Therefore, as previously stated, there was 7/8 (.875)” clearance between the existing rims and the steering arm; this would be reduced by (11.44” – 10.725”) or .715” leaving a clearance of (.875” - .715”) or .16” (5/32”) too damn little.
Possible solutions are two fold, one, my assumptions on the offsets of the 8.25” rims are incorrect or calculations are wrong. Possible solution—to have Big Mike at Spartan have someone take a 9“ rim and check clearance on a Mountain Master Chassis with Meritor front axle (2016 Aspire). Second solution—find a rim with less offset or add a filter plate to move the rim away from the hub by a ½“ or so. Both of these solutions would need to be approved by Spartan and Entegra.
So still looking for a clean solution, Help. I will forward this to PJ at Entegra and Big Mike for their insight.

Like to see the solution to this issue as I would also entertain this change if we don't pickup a 2018

[edgray]

Originally Posted by Gary.Jones

Not the answer you want..... but why would you not replace your Goodyears with 295 Michelins?

Gary

Gary: I may have no choice but to stay on 295/80 tires based on some of the EXCELLENT replies above. The Michelin specs I found online show the 315s require a min. 9" rim width, so I will begin looking for the "other" pressure chart referred to by Steve Ownby. Also, I've been told Michelin offers a 305/80 size in their XRV product, but I've not yet checked the specs it requires. I'm wondering if anybody has considered using the 305 XRV from Michelin.

To answer your question, I was hoping to increase the size to get the load range L so I could run lower pressures. My 2016 solid axle is rated @ 15,660 pounds. We are not heavily loaded for this trip, and I was shocked to see a Cat scale showing my actual FA weight is 15,100, after filling the fuel tank and with 2 adults in the front seats. Based on my interpretation of their pressure chart, I need a min. of 120 PSI in my GY 670RV to support that weight, which is only 5 lbs below the MAX shown on the sidewall.

I also want to thank all the other members for their replies and say to Jolar01 that I appreciate his attempt to get "professional" recommendations from PJ and Big Mike.

[Steve Ownby]

Originally Posted by edgray

Gary: I may have no choice but to stay on 295/80 tires based on some of the EXCELLENT replies above. The Michelin specs I found online show the 315s require a min. 9" rim width, so I will begin looking for the "other" pressure chart referred to by Steve Ownby. Also, I've been told Michelin offers a 305/80 size in their XRV product, but I've not yet checked the specs it requires. I'm wondering if anybody has considered using the 305 XRV from Michelin.



To answer your question, I was hoping to increase the size to get the load range L so I could run lower pressures. My 2016 solid axle is rated @ 15,660 pounds. We are not heavily loaded for this trip, and I was shocked to see a Cat scale showing my actual FA weight is 15,100, after filling the fuel tank and with 2 adults in the front seats. Based on my interpretation of their pressure chart, I need a min. of 120 PSI in my GY 670RV to support that weight, which is only 5 lbs below the MAX shown on the sidewall.



I also want to thank all the other members for their replies and say to Jolar01 that I appreciate his attempt to get "professional" recommendations from PJ and Big Mike.

The 305 is a 70 profile instead of 80. It carries the same weight as the 295/80 XZA Energy and a little less than the X Coach. Using the 315s on 8.25 wheels, you can come in just under the 15660 rating at 115 psi. That configuration tops out at 16000 pounds at 120 psi. That is the top pressure rating for 8.25" wheels. The 9" wheels with the 315s are rated at 18180 pounds at 130 psi. Obviously, you can gain lots of Head room if you can fit 9" wheels.

The X Coach in 295/80 might be your best & simplest answer. They will carry 16540 pounds at 123 psi.

I just looked at the Continental inflation table for their 315/80s. They show the 9" wheel as the design size but don't deduct from weight carrying or max inflation for the 8.25" wheel. They still show a max weight of 18,180 at 130 psi.

[Mr_D]

Originally Posted by edgray

Based on my interpretation of their pressure chart, I need a min. of 120 PSI in my GY 670RV to support that weight, which is only 5 lbs below the MAX shown on the sidewall.

Here it is again:
The pressure on the sidewall of a Michelin RV truck size tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire. NHTSA defines a truck tire as those used on anything with a GVWR of 10,000#'s or more.

From the Michelin RV Tire Guide:

"If you look at the tire's sidewall, you'll see the maximum load capacity allowed for the size tire and load rating, and the minimum cold air inflation needed to carry the maximum load."

From page 6 of the GoodYear RV Tire and Care Guide:

"How much air is enough?
The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as the minimum cold air inflation, needed to carry that maximum load."

From TOYO:

Q: What are the consequences of inflating the tires to accommodate the actual loads?
A: If the inflation pressure corresponds to the actual tire load according to the tire manufacturer’s load and pressure table, the tire will be running at 100% of its rated load at that pressure. This practice may not provide sufficient safety margin. Any air pressure loss below the minimum required to carry the load can result in eventual tire failure.

But then they go ahead and publish a weight/pressure chart allowing lower pressure for RV's!!

From the August 2010 Motorhome Magazine "Tread Carefully" tire article:

The maximum load capacity allowed for the size tire and load rating and the minimum cold air inflation needed to carry that maximum load are located on the tire’s sidewall.

From our owners manual:

Federal law requires that the tire’s maximum load rating be molded into the sidewall of the tire.
If you look there, you will see the maximum load allowed and the cold air inflation pressure required to carry that stated maximum load. Less air pressure restricts the tire to carry a lighter load.

[FreshAir]

Me thinks this might becoming a little complicated.

Here is a little more information regarding putting a 315 Mich. on a 8 1/4" wide rim. I just received this from a Michelin Support Rep. Answers do vary depending who one consults with. Here is an Email conversation I had today with Michelin Rep. Brian

Me :
yes. i want to put 315/80/22.5 on my 8 1/4 wide wheels. replacing GY 295s

Brian : Michelin Support Rep.
"I do see that these 315 wide tires are recommended for a wheel width of 8.5"-9.0". so mounting them on a 8.25" may cause the bead to not properly seal which may lead to slow air leaks on your tires."

Me: Then bad idea?

Brian :
"It may be so we do not recommend it. Newer style wheels and tires have a blocked or flat bead and lip seal surface. For a proper seal these two would need to be flat all along the lip of the wheel. With a wider tire, the bead, or the part that sits on the wheel may sit an an angle not creating a full seal around the tire."

I"m just the messenger.
Pat