I was reading somewhere that if youput larger wheels and tires you should get a bigger ring and pinion set to help the mpgs. but i always thought that if you changed your ring and pinion it would get worse. i had the stock 17s and now i have the stock 20s and i was wondering if i switched from 3.55 to 3.90 my mpgs would go up?

Thanks in advance.

 

only thing thats going to change is the whole diameter of the wheel. in a way i guess it could help because of the extra weight added with the 20. but the higher the gear the more rpms your going to tach on. it will help in town with stop and go traffic because the engine wont strain as much pushing those big ol' meats around, but on the highway, because of the added rpms, your mileage will slightly decrease. if your in the city a lot, go with a higher gear, but if you commute to work and have 40 or 50 miles each way of highway, id stick with the lower gear. i would switch from 3.55 to a 3.92. most of the trucks come with a 3.92. i myself want a 4.56 to help with my 35's. but maybe since your already going to 3.92, maybe a 4.10 would be better. depends on your driving habits and how big the whole wheel is. dodgenitto has a chart that shows what gears for what size wheel and how many rpms are gained. theyll be able to tell you better

 

yup...stock 20's, go 4.10's...for a really fun time..get the 4.56's

 

i drive about 25 miles on the highway each day so i guess i do more highway driving.oh andthe 4.56 are always in the back of my mind but i think the 3.92s or 4.10s would do because when my tires wear i want to go back to some lightweight 18's. those 20's are just too heavy.

 

As mmstar23 said, here is the chart!

http://www.4x4offroads.com/gear-ratio-chart.html

If your Ram came stock with the 275/60R20 tires or if that is the set up you run now, then it would be ideal to run 4:10-4:56 gears! If you are unsure of your tire size, use the tire calculator under the chart to figure it out!

Hope that helps!

 

I've got stock gears and switched to 20's. If I re-gear, say 4.56's, will my SC Flashpaq pick up that mod and adjust automatically or will I have to input the change in the programmer?

 

re-gearin needs no change in terms of speedo calibration or anything else, it's changing tire sizes that speedo adjustments are needed (which sc can do)