Ok so lets take a look at my sig, 38" tires, 3.55 gears.

I've switched to 4.10's and 35's.

Now I havent drove it enough yet to tell but what I'm wondering is which is better for fuel millage?

Large tire, tall gears

Small tire, shorter gears

Any combo of the above.

Start tossing me some ideas.

dan :thanks:

The bigger the tire the more weight you are throwing around no matter the gear set IMHO.+ more contact surface area contact with the pavement.

JMO

:agreed: the bigger the tire the more rollin resitance. Plus the 4.10's and smaller tires are going to have ure RPM's on the highway a lot higher. My buddy has 4.10's and 35's and at 65 he is turning over 2k, that is what I turn at 75. Higher rpm, less mileage.

Ok so say I switch to the 3.55's again and run the 35's?

Before I switched to the 4.10's I could get 20mpg with the 38's and 3.55's.

I need to keep the rpm's up a bit for towing so I can keep the turbo spinning.

With the 38's and 3.55's I either had to tow @ 90 in OD so my rpm's were high enough or tow @ 55 with the OD off. I just want to be able tow @ 75 and keep the EGT's in check.

dan

With either combo you are getting down around a 3:15 gear ratio. Not good for a auto and trying to tow any weight.

Bill

Well 90% or more of my driving is commuting 125 miles pr day.

Just thinking with the 3.55's back in and running the 35" tires I'll be turning a couple hundred RPM more than before. 35" tire is approx 12% smaller.
1700 x 12%= 1904. at that speed the turbo is going still.
It pulled fine before I may add it would just climb to 1300deg a bit too easy for my liking.


dan

i have 33x12.50 's with 4.10 gears city i get great milage 22-24.. high way im doing 2100.. at 70... witch my tires are 5-10 miles off so im doing 75-80 she cruises tho

i have 33x12.50 's with 4.10 gears city i get great milage 22-24.. high way im doing 2100.. at 70... witch my tires are 5-10 miles off so im doing 75-80 she cruises tho

Thats amazing, my buddy is running a 96 with 4.10's and 33's and he only gets 14-15mpg city or freeway. My 00 with 3.53's and 33's gets about 18city and anywhere from 19-23fwy depending on my driving.
Sean

high way dont ask... lol i try to stay off it i get bad milage... thats why i kind of want to get rid of them and get 3.73 for the high way