I have a 92 150, 4x4, sc, 300 I6, 5 spd and it is very high geared, 3.55?
It has 235/75/15 tires. I going to change tires.
Would going bigger help anything? or should I just stay with this size.
kindof want it to sit higher. Its just so dang high geared I do not want to make starting out any more a piain.
thanks

PS anyone have an idea what this truck shouls make on mpg? 125k

 

I wouldn't say 3.55 is a high gear,average at best.Since your truck isn't a speed demon anyway it's not really gonna hurt,but it's not gonna help going to a bigger tire.I know these motors are not rev happy,but i'm sure a set of a 3.73 or lower (numerically higher)gears would help acceleration.A 33/12.50/15 with 4.10 gears and you should be the same as you are now if not a little better off.According to my little chart,a vehicle with a 30in tall tire with 3.54 gears will crank 2181 rpm's at 55mph.Now go to a 4.10 gear and 33 in tall tire at 55 mph and you will be cranking 2296 rpm's.Now obviously different transmissions will vary.This is what I have out of my Jeff's Bronco Graveyard catalog.Hope this helps.

 

Are you sure it's 3.55 gears? Many of those I6 trucks came with 3.08 and 2.73 gears which make for a lot of clutch slipping to get it moving. What is the axle code on the drivers door pillar?

 

My 302 M5OD runs a steady 2k at 70mph with 31 BFG's. Yea, starting out on an uphill run with some idiot on my rear bumper gets my heart going, especially when all they know is where the horn button is and the phone in thier ear. Other than that, I just try and cruise through the gears, and enjoy my ride. I really enjoy that 1st/2nd gear front end hop. I would never go back to an automatic for love or money.

 

If you really have 3.55 gears then going up to 30x9.50x15 tires would be a good upgrade and fit the truck better.

The 300 does not need low gears (numerically higher), since it is a low revving engine and makes low end torque.

If you have 2.73 gears, I would definitely keep the 235 75 15 tires.

 

I think those rpm numbers are for non overdrive 1:1 final drive right? Thats how most of the charts I have seen were. If thats the case then the highway rpm would be a bit lower.

 

What's axle code 18

 

3.55 gears in a 300 I6 is a low gear for that engine. It takes a higher rpm to run 70 on the highway than V-8. If you have an over drive thats better but a lil bigger tire would actually help your gas mileage on the highway an wouldnt hurt it at all around town. My 95' 300 I6 had stock tires an 3.55 then I removed an install 33 12.50/15 got 15 MPG Loaded or unloaded highway or not nothing ever seemed to change it note it got same mileage stock ties or other.but my brothers has 3.08 an it got 19-20 on highway but did really change much by a load in it with stock tires.

 

Ive got a 1987 F-150 300 4-speed with the granny low and 3.08 gears with 31x10.50 R15 tires
I can get 20 MPG on the highway (when im easy on it) and 13 MPG highway hauling an 1985 mercury gran marquis on a car hauler.

and the car hauler has one of those ramps that goes up and catches all the air

(The 87 is in my garage in my profile)

 

OK just got in and looked my axle code is 19. can someone tell me what that is or where to look it up. Should have looked to see what the stock tire size was. I am guessing the 235s.
I would love to get in the upper teens on the hwy and lower teens in town. I live in a small town never go faster than 35 in town.


Which is the better tranny on these pickups? toughness and longivity?
thanks again

 

Axle code 18 is 3.08 ratio, 3800 pound rating.

dn.

 

Ford Axle Code Chart .: Articles