[CHAR250R]

Haven't posted in a while since I sold my 97 F350 2 door. I just purchased another 97 F350, but this one is a crewcab. The 2 door had 355's in the rears, and was comfortable on the hiway around 70-75 MPH. The crewcab has 410's in the rears. I know there will be a difference on the hiway, but how much? What will the truck be comfortable at? Thanks in advance! Charlie.

 

[CHAR250R]

Anyone? Hello? Is there anybody in there? Someone out there must have some info....

 

[Believer45]

Need to be patient. Only 10 minutes from your first post in this thread to the second.

<font color="red">added in edit See below, I am still learning to tell time.</font> /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/wink.gif

As to 3.55 vs 4.10 gears the RPM with 3.55 at 75 mph will be the same as the rpm at 65 mph with the 4.10 gears. This may or may not be what you were hoping.

As to economy, my truck (3.55 rears, 33" tires) gets 2-3 mpg better economy at 55 than at 65 empty, towing @ 4500 lbs 2 horse trailer gets 14.5 mpg at 65 and 15.2 mpg at 55.

 

[ryanPSD]

[ QUOTE ]
Need to be patient. Only 10 minutes from your first post in this thread to the second.

[/ QUOTE ]

You mean 12 hours and 10 minutes. /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/tongue.gif

 

[Believer45]

[ QUOTE ]
You mean 12 hours and 10 minutes. /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]

You, of course, are correct. I go by military time at work and had not made the transition yet.

12 hours 10 minutes is correct, I am also surprised no replies in that time.

Sorry for yet another error in my career here at TDS.com /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

 

[brahamfireman]

Define Comfortable????

I used to get a lil antsy when the tach was wraping around to 3K going down the highway, now I dont care, 3K all day. if I need to go any faster then 75 MPH, then well it must be REALY REALY important.

4:10's and an auto 75 is 2500 RPM

Diesel Rod

 

[Gmanak]

I cruise at 62 to 65 and get decent mpgs but it seems just fine at 70mpg but drops from 18 to 15 mpg. THought I would want 373s but i like the 410s for hills and pulling power.

 

[BadPSD]

i can cruise at 80 at like 2600-2700 rpms and i have 355's it will tach out at like 2800 and just keep on making your rpms faster lol

 

[milner351]

5spd or auto?

auto has more overdrive than the 5spd.

My truck is "happy" at about 65 on the highway, I just can't stand the thought of consistantly spinning those huge heavy pistons and rods at much more than 2500 for long periods of time.... but I'm crazy like that.

I have stock tires, 4.10 gears, and a 5spd, I run about 2200-2300 around 65mpg, and got a best of 19.2pmg doing so.

I wish I could put in a pair of 3.55 front and rear, but the PITA factor along with the cost of the gear sets wouln't pay me back.

 

[blever]

I run anywhere from 65 to 75 on the hwy with no problems. Usually get between 18 & 20 mpg running empty. When towing I run no faster than 60 & get about 11 mpg.

 

[ryanPSD]

It sucks when pulling the toy and trailer, but 3.55's on 33" tires sure is nice. 2200rpm at 75mph. /ubbthreads/images/graemlins/smokin.gif

 

[bbm180]

At 70mph I am a little over 2500 rpm. I get about 16 mpg at that speed. Hoping a new intake will help out a little with the mpg.

 

[jimzpsd]

I've been known to cruise at 80/85 sustained on the turn pikes(I-44, Tulsa, Ok. area) w/no probs. And I'm no where near redline. Here's a good example of a "spinning" diesel, take a look at a typical job site air compressor(diesel powered) or a large elec. generator for a hospital, these things can run 24/7 @ WOT,w/a load, and do.(they're diesels).

 

[Sparkydm]

2200 rpm @ 75 mph seems a little high. 2000 rpm puts me between
73 & 74 mph with the 3.55 gears and 265 X 75 tires. I've verified
speed with GPS and the rpms with AIC. My dash tach reads a bit
higher than the AIC. I trust the AIC more than I do the dash unit.
Am I correct on that? /ubbthreads/images/graemlins/shrug.gif

 

[ryanPSD]

Okay I just drove my truck today and I thought about that on the way home earlier tonight (I drive it once or twice a week now only). I was doing 74-75mph at about 2200-2250.

I haven't recalibrated my speedo since I got the larger tires either, I wonder how much that is affecting things.

 

[CHAR250R]

Good info people. It would of helped if I asked the question in the right forum....

 

[psu927]

[ QUOTE ]
I've been known to cruise at 80/85 sustained on the turn pikes(I-44, Tulsa, Ok. area) w/no probs. And I'm no where near redline. Here's a good example of a "spinning" diesel, take a look at a typical job site air compressor(diesel powered) or a large elec. generator for a hospital, these things can run 24/7 @ WOT,w/a load, and do.(they're diesels).

[/ QUOTE ]

what RPM are you at dude? The biggest thing for me is fuel mileage. Goes way down at those speeds with 4:10s

 

[1997PSD4ME]

i run 70 at 24xx rpms all day long. 14-16 mpg. with 4.10s and 33's.

 

[taz66215]

I've got a stock 96 PSD in a F-350 crewcab with 4.10's I guess. I'm running 215-85-16 BFG Commercial TA tires (previous owner) not my choice, I'd have gone at least to 235's. My engine runs right at 2000 rpm at 60 mph and about 2300-2400 at 70 mph on the dash tach.

I get about 16 mpg highway running empty and about 14 mpg pulling a trailer.

 

[NickKent]

[ QUOTE ]
2200 rpm @ 75 mph seems a little high. 2000 rpm puts me between
73 & 74 mph with the 3.55 gears and 265 X 75 tires. I've verified
speed with GPS and the rpms with AIC. My dash tach reads a bit
higher than the AIC. I trust the AIC more than I do the dash unit.
Am I correct on that? /ubbthreads/images/graemlins/shrug.gif

[/ QUOTE ]

I find a discrepency between the tach and the AIC too. I think the AIC is more accurate.