Community Forums

caryt · 09-24-2018, 09:34 AM

2004 CC Magna 42' 3 slide with the C-15

Going with XzA2's in the front 315/80/22.5's

The rear had 12r's so could replace them with 295/80/22.5on all 6 or do all 315's.

Anyone done this?
Issues ?

Thanks

CarlAda · 09-24-2018, 09:39 AM

Rim size will be a major factor if you can go with 315s (in addition to clearances). I have 315s on the steer and 285s on the drive and tag.

caryt · 09-24-2018, 10:17 AM

9" fronts and 8.25" rears.

the 315/80/22.5's:
Ply Rating: 20
Load Range: L
Loaded Radius: 19.6 Inches
Overall Diameter: 42.5 Inches
Overall Width: 12.5 Inches
Approved Rims: 9.00, 8.25
RPM: 489
Tread Depth: 18 (32nds)
Max Speed: 75 MPH
Max Load (Single): 9090 lbs at 130 psi
Max Load (Dual): 8270 lbs at 130 psi
Tire Weight: 139.6 lbs

The 295/80/22.5's:
Load Rating: 16 Ply
Loaded Radius: 19.1 Inches
Overall Diameter: 41.3 Inches
Overall Width: 11.8 Inches
Approved Rims: 8.25, 9.00
Minimum Dual Spacing: 13.2
RPM: 503
Tread Depth: 16 (32nds)
Max Speed: 75 MPH
Max Load (Single): 7830 lbs at 120 psi
Max Load (Dual): 6940 lbs at 120 psi
Tire Weight: 126.3 lbs

So may come down to the dual spacing, anyone have that spec? 8/10" wider.

I've read that's its been done, but would like currant thoughts:

https://www.countrycoachforums.com/i...?topic=16320.0

CarlAda · 09-24-2018, 11:20 AM

Those Michelins? The 315s I looked at were Toyo and required 9 inch rims, which is why I stayed with the 285s.

Gary at Premier RV had told me that the 315s wouldn't be an issue with spacing, but the rims were my issue.

caryt · 09-24-2018, 11:23 AM

Yes Michelins.

Read some additional posts that Jim Dickman in Junction City documented that the dual spacing of the metric met the requirements for the 315's on a '03 Magna.

CarlAda · 09-24-2018, 11:28 AM

Personally, I'd go with the largest weight capacity tire I could get to fit.

caryt · 09-24-2018, 11:37 AM

That's why I'm looking at the 315's.
@120psi should be 8000lbs which gives me a total of approx 6360lbs additional at the rear.

I haven't a clue what the rear axle weights are, I will corner weigh the coach once I get it.

Just made the deal.

gsander1 · 09-24-2018, 11:52 AM

I have had Continental 315 80s on the rear of my 2003 Magna since 2012.The rims are the original 8.25. No problems.When I replace them in the next year or two
i will probably go to 295 80s.

caryt · 09-24-2018, 12:14 PM

Thanks,

Reason?

Gordon Dewald · 09-24-2018, 12:25 PM

Should not hurt if the rims will take it.

Benefit - all tires are same size so in a pinch you could take a rear to the front in case of a flat? Not sure I would do that as I do not carry a jack or wrenches.

Benefit - you can rotate steer tires to the rear.

Negative - paying more for tires that are not required.

Mr_D · 09-24-2018, 12:36 PM

Quote:

Originally Posted by caryt

That's why I'm looking at the 315's.
@120psi should be 8000lbs which gives me a total of approx 6360lbs additional at the rear.

I haven't a clue what the rear axle weights are, I will corner weigh the coach once I get it.

Just made the deal.

Maybe or maybe not. Depends on why CC set the axle ratings at what they did.
If the tires were set to the maximum the axle rating is then going to higher rated tires gives you nothing.
My rig has a drive axle rating of 20,000#'s (max legal rating at the time). Looking at the axle tag shows that it's actually a 25,000# axle. In my case I can just add air to the existing tires (315/80's). Going larger would be of no benefit.

sanddan · 09-24-2018, 03:58 PM

Whya are you changing from the 12R's?

I'm only asking because we have the 12R's and will be looking at getting new tires in the next 1-2 years.

caryt · 09-24-2018, 04:02 PM

I want to run the Michelins XzA2's.

caryt · 09-24-2018, 04:16 PM

Quote:

Originally Posted by Mr_D

Maybe or maybe not. Depends on why CC set the axle ratings at what they did.
If the tires were set to the maximum the axle rating is then going to higher rated tires gives you nothing.
My rig has a drive axle rating of 20,000#'s (max legal rating at the time). Looking at the axle tag shows that it's actually a 25,000# axle. In my case I can just add air to the existing tires (315/80's). Going larger would be of no benefit.

Here is how I look at it my opinion.

Having tires that are near their rated capacity are not as safe IMO as ones that have extra capacity over whats needed.

Handling improves at least on a 8000 lb pickup, stability improves and since they can run at a lower pressure than max will give a softer ride.

Granted I have no MH experience hence my post.

CC spec was 12r's on the tag and drive

axles. Many go to a 295/80/22.5 because of more choices.

I'm looking at those or the 315's for the reasons stated.