i want to drop my rpms just a little what is the best way to due this . should i change out the rears , i have a 2006 6 speed g56

 

a little taller tire would be a lot cheaper than a complete gear swap.

 

Taller tires above 285 would not work for me due to pulling horse and stock trailers alot. I went with the 3.42 gear change and have been fully satisfied. Did it in December 2007. It was pricey at $1900, but hand calulated I picked up 1.5 mpg in town and 2 on the highway. I also can run 70 at 1950 rpm where before it was 2150 with the 285's. 5th gear is now usable for 55 mph ranch roads and extra heavy loads. It will take about 50,000 miles to pay for itself, but the truck is just more of a pleasure to drive. However, if I had a NV5600, post December 2007 G56, 48RE or a 68RFE I would not consider it because you would then drop rpm's too much if the truck is used for work. Just my 2 cents. Jay Jones

 

If you can, the larger tires seem to be the most inexpensive way to go, though for the old dually you are looking at getting 6. You can also look at a gear vendors unit, but they are fairly pricey.

 

Gear Vendor Overdrive is one heck of a piece of equipment... About 4K installed.

 

Cheapest solution is running a set of 285/75/17 Toyo's with a spacer for the rear wheels. Next option would be swapping out the gears for the 3.42.

MikeyB

 

what size spacer would i need for 285/75/17

 

larger/taller tires is the most inexpensive way

 

Problem with this tire is it is VERY heavy.. stock 265's are 48lbs, toyo 285/70 are 53lbs, and the 285/75's are a whopping 67, almost 20lbs a tire heavier than stock... Thats 80lbs in extra unsprung weight, which is HUGE when your trying to drop rpms for mileage. From what I have read the rpm drop mpg increase in negated by the tire weight increase, so your back at square one.