Is tire upgrade possible

[Brett63]

Does anyone know if moving from a 315 front to a 365 front is possible on an 09 Sig?

[Pampero]

The width of your current tires is 315mm and you want to be 365, that is 50 mm different or 2 inches.

Would your rims accept that width?

You also need to keep the same overall diameter,. How you do that?

Adjusting the profile; if you keep the same profile your tires will be to big.

A "good" tire supplier will advice.

I don't know if you can get the tire size you need, I think for @ 10mm increase on the wider the tire has to go 5% down on the profile. Not doing so will make the tire bigger affecting the speedometer reading which can be adjusted by an Allison dealer.

Profile = a % of the tire width. The result will be the distance from the tire rim to the tire edge.

If your tire is 315/70 R22.5 , the distance is 220.5 mm.

I you keep the same ratio, the length will be 255.5 mm, so the overall tire high will increase by 2.81 inches. 

Do you have the room for it?

Manteining the same ratio WILL require a programing on the Allison transmission. 

 

[Brett63]

I don't believe steer tires have anything to do with speed or the trasmission at all. 

[Gary 05 AMB DST]

1 hour ago, Brett63 said:

I don't believe steer tires have anything to do with speed or the trasmission at all. 

It may affect the ABS.

Gary 05 AMB DST

[Brett63]

7 minutes ago, Gary 05 AMB DST said:

It may affect the ABS.

Gary 05 AMB DST

That it may, not sure. That's why I am asking......lol

[Hypoxia]

I don't think it would affect anything other than the wheel (rim) size capacity and the fit in the wheel well.  When aired down there isn't much room & if the wheel was turned it may contact the fiberglass.  I doubt if ABS cares, it looks at rotation vs. no rotation.

[Gary 05 AMB DST]

34 minutes ago, Hypoxia said:

I don't think it would affect anything other than the wheel (rim) size capacity and the fit in the wheel well.  When aired down there isn't much room & if the wheel was turned it may contact the fiberglass.  I doubt if ABS cares, it looks at rotation vs. no rotation.

But doesn't the ABS control the ATS?

Gary 05 AMB DST

[Walker]

I believe you would have a very good chance of hitting the fiberglass.  There is not much clearance with the stock tires.

[Brett63]

46 minutes ago, Gary 05 AMB DST said:

But doesn't the ABS control the ATS?

Gary 05 AMB DST

They work in tandem, but neither work off of the steer tires per sey. ABS just runs on a tone ring, it doesn't care about anything as long as the ring continues to spin. Yes I would have to change wheel size to accomodate. I have actually 3-4" clearance when aired down completely between tire and fiberglass. I always make sure wheels are straight before dropping air as even the 315 would contact if turned. 

I know many coaches have converted the steer and tag to 365 just didn't know if anyone had done it on a Monaco.

1 minute ago, Walker said:

I believe you would have a very good chance of hitting the fiberglass.  There is not much clearance with the stock tires.

There is on mine. I will go out with a tape in a minute. But aired down completely I have between 3-4" clearance

 

[Walker]

The clearance issue is in a tight turn and then throw in slightly uneven terrain and  things could get ugly.

[Brett63]

Just now, Walker said:

The clearance issue is in a tight turn and then throw in slightly uneven terrain and  things could get ugly.

Yep, understand that, that's why I said I would have to go out with a tape and measure......lol I don't know if there is room or not. All the newer highend coaches have moved to 365 as handling and ride is vastly improved. We shall see. I know a few guys that have removed their drives and replaced with 445 super singles. I ran those on my tractor and loved em.

[Jim McFarland]

What is the advantage to going to a larger tire?

[vito.a]

Brett, 2009 was the first year for Monaco installing a 315 front tire on the Signature and Marquis.  Prior to that they used a 295/80-22.5.  Several of us with older coaches have installed 315 front tires.

I explain this because the chassis is the same and I doubt you can fit a 365 tire on the right front.  When the steering is turned left, the right front 315 sized tire is very close to the airbag mount.  A 2008 Navigator owner said the 315 did not fit his coach.  (I suspect it was not at ride height).

I think there is a close equivalent to the 295/80-22.5 in a Super Single for the drive axle.  They are expensive, but have a lower rolling resistance and will save on fuel mileage.  

To answer Jim's question as to why a larger tire.  The larger size front tires have a higher load range at a lower tire pressure and ride better.  

Edited September 25, 2021 by vito.a

[Pampero]

I miss the "front" part of the original question.

I guess you will never be able to rotate tires.

My 2000 Windsor has 365/80

 

[Brett63]

20 minutes ago, Pampero said:

I miss the "front" part of the original question.

I guess you will never be able to rotate tires.

My 2000 Windsor has 365/80

 

Thats why most that do the convert, or the ones that come with 365 also have them on the tag.

[Ivylog]

I’ve been running 315s on the front for 10+ years…. no ABS issues. Was a tight fit on the 42’ Dynasty but plenty of clearance to the airbag on the 45 Navigator. I would be concerned that a 365 on a wider rim would rub on the side of the tire in a tight (full lock) turn.

A Intregra  Connerstone was parked next to me this week and I was surprised it had 365s on the front and 6 315s on the rear with a ISL engine. If it weighed enough to need that much tire, (he had not weighed yet) it had to be a slug.

OP, I assume you have 315s all the way around… over kill, but you’re probably running 85 in the drives and 70 in the tags. I’m replacing the cracking 295 Michelin’s on the rear Monday with 11R22.5s…don’t need the load carrying of the 295s and I’m on the heavy side. Putting a 365 on the tag would be even more absurd plus only Michelin makes a 365… reason enough to not go to 365s.

Edited September 26, 2021 by Ivylog

[dl_racing427]

22 hours ago, Hypoxia said:

I don't think it would affect anything other than the wheel (rim) size capacity and the fit in the wheel well.  When aired down there isn't much room & if the wheel was turned it may contact the fiberglass.  I doubt if ABS cares, it looks at rotation vs. no rotation.

ABS will definitely care.  It looks at individual wheel speed.  There's some allowance built in to account for tire wear and individual variation, but a significant difference in diameter between tires on the same vehicle will cause problems. Changing ALL tires would likely not cause an ABS fault.
And yes, it can also affect ATC, as the same sensors are used.

[David Pratt]

Despite all the previous posts the simple answer is "NO THEY WILL NOT FIT". The newer coaches,(2009 and UP), that have the 365 tires on the steers are either built on the newer Freightliner or Spartan IFS chassis's that are designed to run with these tire. You will not be able to install them on the Roadmaster RR10R or RR8R chassis without some dire consequences. The 315 will be the largest tire you might safely install on your steer axle.

Some of the higher end coaches, Prevost, Foretravel ih-45 and Newell have also started using the 365 on the tag axle. They are doing this to be able to handle the Increase in GVW of these coaches.

For Example; my ih-45 Travel weight is 53,000 lbs.

[Donflem]

😳58,000 wow. I’m amazed every day at the stuff I hear and learn from you guys. I’m so grateful for this blog.

Don

[Brett63]

17 hours ago, Ivylog said:

I’ve been running 315s on the front for 10+ years…. no ABS issues. Was a tight fit on the 42’ Dynasty but plenty of clearance to the airbag on the 45 Navigator. I would be concerned that a 365 on a wider rim would rub on the side of the tire in a tight (full lock) turn.

A Intregra  Connerstone was parked next to me this week and I was surprised it had 365s on the front and 6 315s on the rear with a ISL engine. If it weighed enough to need that much tire, (he had not weighed yet) it had to be a slug.

OP, I assume you have 315s all the way around… over kill, but you’re probably running 85 in the drives and 70 in the tags. I’m replacing the cracking 295 Michelin’s on the rear Monday with 11R22.5s…don’t need the load carrying of the 295s and I’m on the heavy side. Putting a 365 on the tag would be even more absurd plus only Michelin makes a 365… reason enough to not go to 365s.

Yes I have 315's everywhere and I run 85 in all six on the rear and 100 in the steers

[Ivylog]

David, what are your axle weights and psi on your Foretravel?

[Paul J A]

I ran 315's on all 8 positions on a 07 Executuve for 78K . 

[birdshill123]

Pompeo. Why would anyone rotate tires on a MH? Definitely  not a standard practice and of no value. Tags and Duallies wear differently than steers. Besides most owners change tires due to age not wear.

 

[David Pratt]

12 hours ago, Ivylog said:

David, what are your axle weights and psi on your Foretravel?

Steers are at 115 psi, Drive axle tires are at 105 psi

 and Tag axle tires are at 95 psi

[Ivylog]

4 hours ago, David Pratt said:

Steers are at 115 psi, Drive axle tires are at 105 psi

 and Tag axle tires are at 95 psi

So working backwards your steer are 18,500, drive 24,000, and tag 15,500… more or less. So the tag is probably putting 3,000 lbs on the steers so the drive is legal at 24,000. Time to put the tag in front of the drive like they were years ago.

Edited September 27, 2021 by Ivylog