Not to take the thread off track, but I've got 265's with 4:10's and run 2300 @70 mph. I wish I knew a way to drop those RPM's! What's the biggest tire I can run on my 2WD?

 

banks i've got a 3500 w/4:10s with a six speed. when i'm running up past the 75ish zone, my rpms are up there around 2700 mark. my truck sounds like its screaming. its so very noisy. kinda like a hot rod truck. makes me nervous hearing it so loud but i constantly hear reassuring comments that its designed to work that hard for extended periods.

 

Yes, it's designed to be safe at that level, but if it's not necessary, why do it?

If you want high revs, use the S2K or GSXR in your sig

jlh

 

My truck with the old five speed in it ran for over 100,000 miles at 3000 rpm pulling loads before I started using fifth down hills and later all the time. Everyone said it would not hold loads in fifth due to the nut. When taking the engine down for a seized piston, the engine wear was reasonable.

I contacted Cummins and they said that was well within the operating range it was designed for and would be fine. I sure do like it at 2000 better though, even though the oem engine would never have pulled the loads at my rpm's now.

 

When you guys are comparing cruising rpm, don't forget the notable difference in OD ratios from the stick to the auto......regardless of rearend gear, the 5spd will rev about 300 rpm higher than the auto because of the different OD ratios......

 

allright, allright, i am sorry that i started an argument and turned a good thread into a bad one, i think it would be very wise to drop it and let he who thinks he has 4.10's think he has 4.10's and he who thinks he has 3.55's has 3.55's i told ya'll it would be a sore subject, but i KNOW that i drove a 7.3 ford non turbo with a .76-1 standard overdrive ratio with 4.10's and the speedometer was set to ford specs and the tacometer worked just fine, it was screaming at 2700-2750 rpms at 70 mph and i had a 4-k gks in that truck and the i.p. turned up to the max and it would run like a scalded dog till it blew up at over 350,000 miles, i think the engine would have lasted a lot longer if it would have had a higher gear rear end. i wish somebody in here knew exactly what % of 1-2nd gen dodges actually had 3.55's and what % had 4.10's, i think it would be a fun fact sort of thing to actually find out. and could someone in here tell me what my 94 dodge diesel would be running at 70 in 5th gear with dodge factory settings on the speedo?? since my tach and speedo don't work.

 

Not quite sure where there is an argument or a bad thread. You will be doing about 2300 at 70mph, not 2700. I have 3.55, 6 speed, and 32 inch tires, turn about 1950 at 70. Was just about the same with the 5 speed. The smaller tires (235-85) turned about 2000 at 70, but these Michelin Ribs are larger at 32 inches.

2300 rpm may be noisey by your standards but certainly will not hurt the engine in any way. Running empty at 70 I am sure the 3.55 gears have better economy. But this would only be in effect on highway driving, I can't see where in town it would matter much.

 

Just for reference...

Stock 2002 with 3.55 gears in 5th gear and with 265/75 R16 Tires (31 Inch)...

55 MPH ~ 1,600 RPM's
65 MPH ~ 1,900 RPM's
75 MPH ~ 2,200 RPM's

Or

4th Gear

55 MPH ~ 2,200 RPM's

Just for reference proposes...

 

Please GOD no more ratios. I have stock tires. You all debate alone. My truck says 4.10's and at 2200 +- I hit close to or 70 mph.

 

I guess it's a information overload... It's all good...