Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

Art-n-Marge · 04-28-2010, 09:33 AM

My conversion from an 2006 F-250 to a 2006 F-350 has finally been completed!

Last year, I did the research on the parts difference for the F-250 versus an F-350. With everything else being equal (engine, drivetrain, brakes, shocks, differential, etc.) I found the physical differences were an additional leaf spring and brackets and the tires & wheels (larger to support the heavier weight). I also found that many F-250s have some of these component but the pillar sticker was certified for the F-250. I also found that other truck combinations for different years and other makes and models may require different modifications.

After completing the suspension modification (I posted this experience last year), I waited until my tires wore out before upgrading the wheels and tires. But it was taking months, so I went ahead and found wheels on Ebay and had new tires put on (including the spare). I settled on the Michelin M/S2 LT275/70R18 because they had the desired load rating I needed. The last step was having Ford recalibrate the PCM for the larger tire/wheel size. The service tech mentioned the larger tires could cause "fuel starvation" if I had not had this adjusted. You learn something new every day. It made more difference that I realized. When I had first gotten the wheels and tires replaced something was different and I couldn't quite figure it out. After getting recalibrated, I realized it was the shifting. It now shifts better - because the larger tires delayed the shifting (possibly causing an eventual subtle power loss especially when towing?).

Anyway, I am done with this project. There is actually one last step to do but since I am a private party (non-commercial) it is optional. The pillar label needs to be changed (to reflect the new weight capability and tire size requirements). This would also result in a new VIN so the DMV knows about this capability (and can charge more for my tags). I am not required to do this, so I won't bother. I will keep all the paperwork for the parts and changes in case anyone needs proof.

Im my case, I have gained 400lbs of FAWR, 900lbs of RAWR, and 1,500 GVWR. The tow ratings are unchanged (12,500 at the bumper and 15,200 for fifth wheel). I was originally 400-500 lbs overweight on the rear axle. Now I have about 400-500 lbs of margin. YAY!

I take this new rig combination out for its maiden voyage this weekend. The only thing left to check is the bed clearance. The truck sits about 2 inches higher now, and I had 8" of bed clearance before. Now I will probably be at 6" which is the minimum for this measurement. Oh well, at least I won't have a weight problem unless I eat too much. It just never ends.

A special thanks to MOCer Steve S. for providing his pillar sticker to confirm my numbers and to many other MOCers who provided support.

Take care all!

04-28-2010, 09:33 AM	#1
Art-n-Marge Montana Master Join Date: Apr 2009 Location: Murrieta Posts: 5,816 M.O.C. #9257	It's about time I got it done... My conversion from an 2006 F-250 to a 2006 F-350 has finally been completed! Last year, I did the research on the parts difference for the F-250 versus an F-350. With everything else being equal (engine, drivetrain, brakes, shocks, differential, etc.) I found the physical differences were an additional leaf spring and brackets and the tires & wheels (larger to support the heavier weight). I also found that many F-250s have some of these component but the pillar sticker was certified for the F-250. I also found that other truck combinations for different years and other makes and models may require different modifications. After completing the suspension modification (I posted this experience last year), I waited until my tires wore out before upgrading the wheels and tires. But it was taking months, so I went ahead and found wheels on Ebay and had new tires put on (including the spare). I settled on the Michelin M/S2 LT275/70R18 because they had the desired load rating I needed. The last step was having Ford recalibrate the PCM for the larger tire/wheel size. The service tech mentioned the larger tires could cause "fuel starvation" if I had not had this adjusted. You learn something new every day. It made more difference that I realized. When I had first gotten the wheels and tires replaced something was different and I couldn't quite figure it out. After getting recalibrated, I realized it was the shifting. It now shifts better - because the larger tires delayed the shifting (possibly causing an eventual subtle power loss especially when towing?). Anyway, I am done with this project. There is actually one last step to do but since I am a private party (non-commercial) it is optional. The pillar label needs to be changed (to reflect the new weight capability and tire size requirements). This would also result in a new VIN so the DMV knows about this capability (and can charge more for my tags). I am not required to do this, so I won't bother. I will keep all the paperwork for the parts and changes in case anyone needs proof. Im my case, I have gained 400lbs of FAWR, 900lbs of RAWR, and 1,500 GVWR. The tow ratings are unchanged (12,500 at the bumper and 15,200 for fifth wheel). I was originally 400-500 lbs overweight on the rear axle. Now I have about 400-500 lbs of margin. YAY! I take this new rig combination out for its maiden voyage this weekend. The only thing left to check is the bed clearance. The truck sits about 2 inches higher now, and I had 8" of bed clearance before. Now I will probably be at 6" which is the minimum for this measurement. Oh well, at least I won't have a weight problem unless I eat too much. It just never ends. A special thanks to MOCer Steve S. for providing his pillar sticker to confirm my numbers and to many other MOCers who provided support. Take care all!