Am General M920 tire sizing

[AMgeneral3945]

Hi, we bought an Am General M920 for farm use, we will be using to haul liquid manure. We mounted a 4800 gallon tank on the back to do so. I have been working on tires for the truck and I had the rears retreaded with a more aggressive tread. The tread is BLSS from bandag, which looks like it will work really well. The one problem I have is finding wider tires for the front. I was going to use the Michelin xzl non-plus 395/85r20 but they are not able to retread that wide of a tire. The only reason I was going to have them retreaded was, so that all tires would hopefully be the same diameter. My question is would it still be okay to use the 395/85r20 or try to find a tire size that is closer to size? The diameter of the recapped 11.00-24s are 47.6 inches and the diameter of a new 395/85r20 is 46.8 inches. Is the diameter difference too much for the 8x6 Am General? We would only turn the 6 wheel drive on in the field. Any advice would be appreciated.

Thank you,
Grant

 

[simp5782]

Will work as long as you use the front axle offroad only. Redo your power divider switch so you can have a switch for your power divider to pull on or offroad and a switch for the front axle engagement.

 

[silverstate55]

The only real issue you’ll have is fitting the 20-inch wheel over the front drums; the valve stem will interfere with the figment. You’ll either have to grind down the front drums or use a 22.5-inch wide flotation wheel with the valve stem mounted outboard.

 

[AMgeneral3945]

What do you mean by, redo the power divider switch. Wouldn’t turning the front axle switch off work?

 

[simp5782]

What do you mean by, redo the power divider switch. Wouldn’t turning the front axle switch off work?

You want 2 switches. One to engage the front axle. And a seperate one to engage the front tandem axle rather than both being locked in when you flip the current dash switch.

 

[AMgeneral3945]

Ok I see what you mean, but what is the benefit of doing that? Could there be potential failure with the drives or is it just having the option of the front axles locked without having to have both the front axle and front tandem axle locked at the same time.

 

[simp5782]

You will have both rear axles with lockers pulling together on their own rather than just 1 axle on its own. Gives you more power offroad it would also allow you to unlock the front end but leave the rear locked in for making turns in a field and what not. Allows for more power to the ground for on road use if you are loaded when you have low traction without increasing turning radius or front driveline wear

 

[AMgeneral3945]

That would be nice to have. Thanks for the help. Is it hard to wire in another switch?

 

[simp5782]

No. The switch you seek is napa/haldex 229635RX. You will remove obe of the delivery lines from the main switch and run it to it. You will have to add a supply air line from a fitting on the firewall or wherever you want to put the switch. You will simply install a plug in the port you removed the line and air fitting from on the original switch

 

[AMgeneral3945]

Ok, we’ll probably end up doing this. Seems like a nice option to have. Thanks for the idea and help