Top speed with 33" tires on your FJ/BJ40

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I have been in many debates with a friend who says going from 31" -> 33" tires will not make much difference in speed on freeway. Since these rigs don't have 5th gear, I'm doing about 2800~2900 RPM while cruising at around 60mph. I feel like the engine is producing more than enough power at those RPM to sustain the speed and should be going closer to 64mph.

I have a 2B diesel engine. Please post your model, engine, your speed at 2800RPM with 33" tires. Thank you!
 

1911

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Do you really need to drive an off road designed vehicle at 70 mph?

I drive mine out to drilling rigs for my business frequently. Once out by Pecos, TX on I-20 where the speed limit is 80 mph and there are only two lanes in each direction. It's dangerous NOT to drive at least 75 even in the slow lane, especially at night. My 40 did it (went 75-80 mph), but I won't be doing that again any time soon. :wideyed:
 
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No working speedo and no tachometer so cant tell you exact speed and rpm, but i was cruising with my F and 33s at 75mph
6A3B4CD2-65BD-4A58-A2D3-FB52110465E2.jpeg
according to my cousin who took the pic.
 
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Ohh, well I should have paid more attention. I can only speak of my 3B Troopy for now. I can do 70 with 33's and a 4 speed. However I don't think the tranny enjoys it and cannot wait until 5 speed is installed.
I am not a safety conscious freak (was a paramedic 25 years ago) and have done some pretty stupid things in my life but as I get older the desire to go faster in these rigs is less and less.
 

David*BJ70

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@CookieBird -> Your BJ41 have 4.11 gear ratio.

I don't have RPM on my BJ42. It was equiped with a 4spd and now a 5spd. My gage is the engine sound. Even if it is possible, I would not drive a 2B diesel at 2900rpm. The engine noise at that RPM should be borderline unpleasant.

BTW, asside of some JDM 40 (most likely diesel) and some few other 40 with LX trim, none of them was equiped with OEM tach.

I'll say, put 33. It will make a difference on RPM... let say +/- 5% less with each additional inch of tire.
 

JDNs78FJ40

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I have 33's, 4 speed 2F with 4:11 gears. Have hit 65-68 on the freeway using GPS and was pushing 2900 RPM for sure based on my sniper monitor.. Not the most enjoyable thing I've done, but will do from time to time. Personally my rig isn't made for the freeway. Mine has a sweet spot of 40-50 mph.
 
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I have 33's, 4 speed 2F with 4:11 gears. Have hit 65-68 on the freeway using GPS and was pushing 2900 RPM for sure based on my sniper monitor.. Not the most enjoyable thing I've done, but will do from time to time. Personally my rig isn't made for the freeway. Mine has a sweet spot of 40-50 mph.
Thanks to everyone that replied - it sounds like I could be cruising at around 65mph with the 33" tires. Because right now I'm barely going 60mph and if I want to go faster I have to do 3000rpm which is not sustainable.

BTW I don't feel much difference in engine noise between say 2800 and 3000RPM. I'd say that at around 2500RPM the engine noise is less but if the speed limit is 75 then the semi-trucks start over-taking me.

Sounds like I should upgrade to 33" slim, like 10,5" width tires and that would make me get there. So I'd need a 2.5" lift too
 

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