What RPMs @ 75 mph

[tracker8wr]

i have a 97 crew cab 250 4x4 with a ZF5. im running 2650-2700 rpms at 75 mph. i was wondering what everyone else is running at this speed. i'm pretty sure i have 4.10s but i havent pull the cover to verify it. thanks for any info guys.

[97powerstroker]

yea thats 4.10s,im at 2300-2400 in 75 and i have 3.55's

[harley1rocker]

thats what im running at 75,bout a 1/4 inch above 2500 rpm should be 80mph

[Nitro41]

yup 4.10 gears for me. too i am runing reight at about 2500 at 70 mph on 33" tires

[Jarrod B]

my 4.10s at 70 was 2300ish

[kanuck15]

75mph is 2500 on the nose for me and thats 4.10s

[bucwheat]

Originally Posted by Jarrod B

my 4.10s at 70 was 2300ish

Same here Jarrod.

[tracker8wr]

Ok thanks fellas. i just like to go when i travel and am afraid to run it at 80mph. so 3.55s or 37s. the should yield about the same result. the truck would look alot better on 37s. whats ya'lls opinion on towing. i very rarely pull more than 10k lbs. i run 37" iroks on my 07 and it pulled fine. i am planing on swamps 1.5s and custom chip hopfully not to much longer because i need to change my head gaskets and wiring and have 2 injectrs going.

[Jarrod B]

well, now our 3.55 idi zf5 is around 2100 at 70. so not likely with 3.55s at 80mph.

[tracker8wr]

well my goal was to be able to run 80 and run the ame rpms i was running at 75. so running 2700 rpms at 80 mph instead of at 75. i would travel at 75 towing but unloaded id like to be able to bump it up.