Just upgraded TV tires

[Watsons]

Just an info message...
We have a 2012 Ram 3500 which came with 17" rims. As with a lot of people our pre purchase loaded pin weight calculation was shy by a bit so we ended up heavier than we thought.

Scaled rear axle with trailer loaded for bear and full fresh water tank at 6200 lbs.
There is no choice for 17" tires above the 121 load index. (3190 lbs) which bothered us.

We found some 18" factory rims and Firestones that have 125 load index (3638 lbs).

It raised the truck little more than 1 inch and messed with the speedo slightly but now we have comfort factor at least with the tires lol..so 'happy campers'

[eagleback]

Originally Posted by Watsons

Just an info message...
We have a 2012 Ram 3500 which came with 17" rims. As with a lot of people our pre purchase loaded pin weight calculation was shy by a bit so we ended up heavier than we thought.

Scaled rear axle with trailer loaded for bear and full fresh water tank at 6200 lbs.
There is no choice for 17" tires above the 121 load index. (3190 lbs) which bothered us.

We found some 18" factory rims and Firestones that have 125 load index (3638 lbs).

It raised the truck little more than 1 inch and messed with the speedo slightly but now we have comfort factor at least with the tires lol..so 'happy campers'

You can go to the Ram dealer and they can calibrate the speedometer for you. They just flash the computer.

[catzr]

i have done the similar swap. 18s with firestones for the summer,
17s with hancooks for winter. The truck is calibrated for 17s.
I have checked it with my GPS. The general rule I use is,
speedo says 50, actually 51
says 60 actually 62
says 70 actually 73
says 80 actually 84.
The diesel will just roll out with no issues.
My best interstate driving unloaded fuel economy is at 78
just under 2000 RPM. Love it.

[EvilDoer]

Question for those of you with bigger wheels. My Ford owners manual has a table for towing capacity. There is a separate row for the optional 17 inch rims with lower towing capacities vs the stock 16s, with the same motor, transmission, and gears. Is there a further reduction in towing when moving up to 18s?

[LiftedAWDAstro]

The diameter of the wheel doesn't matter. The size of the tire does. You need to look at the original spec'd tire and see what the diameter was. If you buy new wheels and tires, get the same overall diameter and it will be just like there was no change. If you go too much wider, you may notice a little change in pulling power simply due to extra rolling resistance.