ok guys with 5 speeds what is your mph at 2k i was once told by a guy with 4.10's that his mph at 2k was about 70 so i assumed mine was 4.10's as well I hit 70 at about 2200 so sounded about right i can take off in second gear all day long easily however i finally decided to take a look at the sticker under the hood (dont know why i just now did) and it says axle ratio 3.5?? we have a ford f350 psd with 5 speed and 4.10 rear and its RPMs are about the same as mine at the same speeds?? i dont know is it possible that the previous owner had the 4.10 install after market or is it just not a 4.10?? Any info would be much appreciated!

My 3:54 runs about 1850 at 75mph

Mine runs the same. About 1850-1900 @ 70. What are your rpm's at 55mph out of OD? I run 2100.

70 mph = 2100 rpm<br>75 mph = 2250 rpm<br>80 mph = a little less than 2500 rpm<br><br><br>CR

4.10s -&gt; 2000 RPM = 62 MPH (with 305/70R16s) 19MPG

To do 70 with 4.10's it takes about 24-2500 rpm's

I've got 4:10&quot;s with 285/75 R16 tires and i'm running 2400@70 MPH

<br> With 3:55 gear, RPM is 2000 @ 70 MPH.

Aparently my tire size, (yes, the speedo was corrected and proven with a GPS) and the 6th gear help.....80mph = 2000rpm's with 3.54's<br><br>Later, Rob

It all depends on what tranny you run. The stock tire my truck came with were 265/75/16's. With 3.55's my truck goes 70@2000rpms. My buddy has on 02 with an auto and same gears and tires and he runs 1900 @ 70mph. The manual six has a little lower of an overdrive. My old powerstroke had 4.10s and the same size tire and it turned 2200 @ 70mph.

I have a 99, 5 speed stock 245/75R16's, 3.54's and I run 2200 at about 70 mph<br><br>

Thanks for the info guys mine is a 5 speed with 315 75R16 tires i will have to check the rpms and mph when i go home and i guess i will be able to tell then. I mean the sticker says 3.5 but it feels so low maybe not though i guess if i want or need to i could always switch to 4.10's anyone ever done this or know of priceing?? thanks

<br>Aparently my tire size, (yes, the speedo was corrected and proven with a GPS) and the 6th gear help.....80mph = 2000rpm's with 3.54's<br><br>Yep, that's what I get also. Corrected speedo. 2000 = about 80 mph<br>george

ok guys i done some checking on my RPM's /MPH and found that in 5th gear (manual 5speed) at 60 MPH i am exactly at 1800RPM's however i do have bigger tires so if i use one of those speedometer calculators where you put in stock tire size speedo reading and new tire size it tells me that when mine says 60 i am doing 65.59mph so i guess at 1800 rpms i am really doing 65MPH what are anybody's thoughts on this?? i know for sure at 2000rpms i am not doing 80!! i am confused not that it matters one way or another to me i mean the truck runs strong i would just like to know for sure!

<br>i am confused not that it matters one way or another to me i mean the truck runs strong i would just like to know for sure!<br><br><br><br>CTD nuff said <br><br> ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D<br><br> : Eddie : 8)

If you want to correct your speedo, replace the speedo drive gear with one that has 2 teeth fewer. I believe the part number is 520676xx where the xx are the number of teeth. I forget the number of teeth stock with 3.54 gears (31 rings a bell). It is easy to pull out and check (top rear of transfer case).<br>Marc<br>

I've got a '97 with an automatic, 4.10 gears, and 235-85-16 tires and I run just under 2500 rpm at 75 mph.