I.ve got a 2007 dually with 235/80/17 tires on it, what would be the next size up that would fit the standard rims? also is it possible to go to the next size down? I pull a 38 ft 5er at 16500 lbs. so I don't want to compromise that. and 1 final question can you run a different size on the front than the duells on the rear, what I really want to do is lower the rear of the truck 1-2 inches.

Thanks,
racfan9

 

I would not consider going a tire size up with the rig you have. I'm borderline with my truck and rig with 3.73's. I am either going to go with a 4.10 gear or 4.56 gear. I want a 4.30 but no one makes it for the rear. 4.56 is just a little more than I need and will loose MPG running light. I could go 4.10 and drop the rear tire size diameter to get close to the 4.30.

Here is want cummins says about gearing. Select ISB to get started. My target speed for towing my rig is 65mph. My last truck had a 6sp and 3.55 gear. It towed better than my current truck with less hp and torque.

http://www.powerspec.cummins.com/sit...ng/gearing.htm

Please fill out your signature so we all know what you have.

Dave