Super Singles on C4500?

[Mark Rinker]

Anyone have experience with Super Single drives on a C4500 Kodiak? I have seen a few trucks on the road, looking for feedback and information on rim/tire sizing.

Would like to maintain load carrying capabilities as the truck is used to haul 100% of the time. Also would like to increase diameter by about 15% to lower cruise RPMs.

Has the combination of reduced unsprung weight combined with increased diameter improved your fuel mileage? In this 8-9mpg (loaded) game, even 3-5% would be a great improvement!

[murphyslaw]

What are you using this rig for. my concern with wide base tires on a 19.5 is they are hard to find, and would be very expensive to set up. a 19.5 rim for a wide base is gonna be around 4-500 each. and the tires them selves will be around 1000 each. not to mention if you are ever on the road and get a flat and ruin the tire or have a blow out, good luck finding a replacement. The next step up in the 19.5 tire is 245/75R19.5 That is the size I run on my 5500 service trucks and I love 'em, they ride better and look way better. I personally would never run a wide base(super single) on anything I had that ever left the city. you dont see any over the road rigs with supers on anything but a trailer.

[Mark Rinker]

Hauling big boats cross country. I could carry a 'spare' 19.5 with stock rubber on the trailer. No truck spare on board at all today...makes me a little nervous when on the north side of Lake Superior, or crossing the reservations in New Mexico...

How much larger is that tire diameter over stock, expressed as a percentage? I am looking for as much as 15% total reduction of engine RPM between wheel/tire and possibly even new rear gear selection. This 2300rpm BS at 65mph cruise wastes too much fuel...I need another gear!!!

[murphyslaw]

I will pull out the book and see what the overall size difference is.

[DmaxMaverick]

Mark, for the price of new tires/wheels, you could get real close to the Allison 6 speed upgrade. I'm not sure it would work, but it might. Could be worth looking into.

[murphyslaw]

acording to my michelin book there 225/75R19.5's are 32.4" tall and the 245/75R19.5's are 33.6 so you are gaining right a bit over an inch. the 245/75R19.5's are also wider so you need to check your rim width. the aproved rim sizes for the 225 are 6-6.75" and for the 245 are 6.75-7.5. so make sure youre rim is wide enough to properly fit the 245/75R19.5 dont wanna see you have unexpected problems with this.