I have always wondered what my trucks rpm is when going down the road since it just seems like its screaming doing about 50. It has 3:21 gears and 30 inch tires. I know there are calculators and that, but I like to hear from actually people, so is there anybody out there who know what their car/truck does at around 55?

I have a tach, but the trucks at home and I am at college so I haven't hooked it up yet. Another project when summer hits.

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Get out your aluminum magnets!

But mine will be a bit "different" since I have an overdrive gear...With my current set up, I'm at 2400 rpm (or so...there's the width of the needle somewhere in there on the tiny tach) at 55 mph....Previous set up was about 2300 at 65 mph...



-D.Idiot

http://vexer.com/automotive-tools/speed-rpm-calculator

I read that you are looking for real experience, however this calculator matches the speed/RPM's of my 71 /6 D 100 very closely, I used it for a correction factor when I changed between tire sizes.

That is a really cool calculator, I think I've used it before.

I think because of the cracked exhaust manifold the motor sounds like it is spinning a lot faster then what it actually is. The motor is pretty worn out though so I wont find out until I get the tach hooked up.

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Get out your aluminum magnets!

I have 2 cars on the road with 225 slants, 1 has auto trans, 1 has 3 speed manual, both run 3.23 gears and approx. 25" tyres.
I don't have a tach in either, but both cruise easy at 55, and still not screaming at 75.

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Richard (aka Fingers)

My truck must have a worn out motor with the aerodynamics of a brick then, because it seems to drop 5mph when I hit any headwind.

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Get out your aluminum magnets!

The rear end ratio is too tall for 30" tires.
How many miles on the motor?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Looked at my correction sheets for different tire sizes

71 dodge pu with 225 ci / 6 .. 3 spd manual and 3.91 rear end

295/50/15 rear tires about 27 inches tall 55 mph = 2700 rpm + or -
65 mph = 3200 rpm + or -

235/75/15 rear tires about 29 inches tall 55 mph = 2500 rpm + or -
65 mph = 2950 rpm + or -

I generally hold my sustained speed to 60 mph with the short tires or 65 mph with the taller tires.

Well the tires I had on it were done (bad alignment) and one of the high school teachers had a really nice set of goodyears for $75. The motor probably has 145,000 on it, and needs a rebuild (aka exhaust smoke if reved to 3000 rpm)

I finally got the tach hooked up though and with 3.21 gears and 31 inch tires it does about 2400 rpms, but the lock-up clutch isn't hooked up right now.

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Get out your aluminum magnets!