What's everyone's speed at 3k RPM?

[jjvw]

Ehhhh how


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Our Jeeps will eventually go that fast on our long downhills.

 

[TJ_2000]

77-80 mph. 4.0 5 speed 4.88 35”s in 5th gear.

 

[Nicholas]

Same wheel rpm with a bigger tire is going to mean more vehicle speed.
3k engine rpm with the same gearing means same wheel rpm.
Circumference of 35" is 1.0606 times larger than the circumference of a 33".
1.0606 x 80 mph = 84.848 mph.

Edit: Might have misinterpreted the question of "how" here, but I'm gonna leave this here anyway.

No it's fine, I see what your talking about. Wasn't sure if upgrading to a 33x11 or so instead of a 33x12.5 would make much a difference


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[Nicholas]

Our Jeeps will eventually go that fast on our long downhills.

[emoji23][emoji23]exactly Man



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[jjvw]

No it's fine, I see what your talking about. Wasn't sure if upgrading to a 33x11 or so instead of a 33x12.5 would make much a difference


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Tire width does not change the tire diameter.

 

[jodomcfrodo]

Tire width does not change the tire diameter.

In terms of 11" vs 12.5" and performance, the only thing I can think of would be weight. Though I'm not sure if the extra 1.5 inches of width would make a noticeable performance difference. I would imagine you wouldn't be able to notice.

 

[jjvw]

In terms of 11" vs 12.5" and performance, the only thing I can think of would be weight. Though I'm not sure if the extra 1.5 inches of width would make a noticeable performance difference. I would imagine you wouldn't be able to notice.

There would be some increase in rolling resistance, as well.

 

[dla]

4.0, 3 speed auto (32rh), 4.10's on 33's = 72mph

 

[UPJOHN]

50 mph 3rd gear @ 3000 rpms. I'd bury my speedometer if I got 3000 in 5th.
97 with 5 speed, 4.0, 31s and 3.55 gears.

 

[jjvw]

50 mph 3rd gear @ 3000 rpms. I'd bury my speedometer if I got 3000 in 5th.
97 with 5 speed, 4.0, 31s and 3.55 gears.

What are your rpms in 5th at 70mph?

 

[UPJOHN]

What are your rpms in 5th at 70mph?

2000.

 

[TJ_2000]

Question. How many of you have replaced your Speedo gear or recalibrated your speedo? lol it’s interesting that the results seem to be all over the place. Ranging between 50-80 mph. I understand tire size and gear ratio is a factor but I’m curious how accurate these answers really are. A lot of people over look or don’t realize how simple it is to change out the speedo gear.

 

[jjvw]

Mine is corrected with a SpeedoHealer and was calibrated with GPS.

 

[jjvw]

2000.

Something is off. Grimmjeeper says you have a tire with a rolling circumference of 33", meaning you have a tire closer to a 35".

 

[UPJOHN]

Something is off. Grimmjeeper says you have a tire with a rolling circumference of 33", meaning you have a tire closer to a 35".

Maybe my tach is off. It reads 1800 rpms @ 60 mph in 5th. My speedometer is dead on with GPS.

 

[jjvw]

Maybe my tach is off. It reads 1800 rpms @ 60 mph in 5th. My speedometer is dead on with GPS.

GJ says 1800rpm is 63mph. Also with the larger tire. You're sure that you have 31s?

 

[UPJOHN]

GJ says 1800rpm is 63mph. Also with the larger tire. You're sure that you have 31s?

Yes. 31s. Came with 30s new.

 

[Markus]

Just checked this morning. A bit over 80 (by speedo only) with my ‘05 sport in 6th. Running all stock with 3.73s.

 

[Tim Redman]

about 74 MPH @ 3000 RPM in 4th gear (I didn't feel like trying to do 3000rpm in 6th gear; don't like cleaning up poop, especially mine)
05 Wrangler X, 4.0 I6, NSG370 6-speed, 3.07 gearing, 33" tires, 26 tooth speedo gear replacement

 

[WWII Jeeper]

2006 TJ X, 4.0 , 6 spd man, 373 gearing, LT265/75R 16 tires, with proper speedo gear change, and 1 inch body lift: 6th gear = 84 mph @ 3k.....very comfortable solid ride, no cleanup during or after test run

Ray