Dodge RamCharger Central banner
1 - 4 of 4 Posts

·
Registered
Joined
·
172 Posts
Discussion Starter · #1 ·
I remember somewhere on here there is a formula for this. I have a 86 w150 with 3.23s in her. I just rebuilt the 318 which seems to be running good. I am wanting to run between 33s to 35s. Right now i have the 235s on it and it is real slugish on the take off. When I rebuilt it I put in a little hotter cam the new mp 340 grind. At about 65 she will shit and get. Going to larger tires I know I will have to change the gearing, I know the rpms go up with the gearing going down, will the larger tires offset this?Does anyone remember where that formula went?Thanks
 

·
Registered
Joined
·
8,924 Posts
www.4lo.com has the calcs
 

·
Premium Member
Joined
·
4,879 Posts
(gear ratio)*(stock tire diameter) / (new tire diameter) = effective gear ratio

-SM
 

·
Registered
Joined
·
412 Posts
(highway speed) x (gear ratio) x 336 = (big number) / tire size


so mine would be 60 X 3.54 x 336 = 71366.4 / 31 = 2301RPM

that is what your 4th gear highway speed and RPM would be.


So yours would be 60 x 3.23 x 336 = 65115 / 33 = around 1900-2000 rpm = gutless wonder :p


a friend of mine has a modified 400 big block with 4.11's and 33'' tires and it hauls.
 
1 - 4 of 4 Posts
Top