Tach Question

[southerncruiser62]

What are most of you taching up to when running say around 75-80, i am at about 2800-3000, in my 62 i was only around 2500, was just curious as to if this was common

Greg
94 FZJ80

 

[MrZumma]

Doing a quick calculation with 32" tires, I come out with 77mph @ 2500rpm and 85mph @ 2800rpm. This does not take into account wind resistance and other factors that will affect these results...

I must say though, the engine rpm's are a little low compared to what I see with my stock Michelin's... I am thinking I see something like 75mph @ 2700rpm's.. But that is off the top of my head... I'll check on my way home from work tonight...

 

[RavenTai]

took a look today 75 = 2500

 

[NorCalDoug]

It's late and I don't want to hit the freeway tonight...but we make sure we're talking about true speed at the RPMs? For some with non-OEM sized tires, the speedometer isn't necessarily correct...

 

[reffug]

took a look today 75 = 2500

DITTO

 

[RavenTai]

It's late and I don't want to hit the freeway tonight...but we make sure we're talking about true speed at the RPMs? For some with non-OEM sized tires, the speedometer isn't necessarily correct...

Different tires will change actual speed the vehicle is moving, as would worn tires to a certain extent but will not change the relationship between rpm and indicated speed unless you added a speedometer correction gear, for reference I am running 265/70-R16's (PO's choice not mine) in Michelin LTX

And :whoops: that was suppose to be 2600 rpm @ 75 MPH, sorry

 

[NorCalDoug]

At aprox. 2350 RPM, the speedometer reads 68 MPH,
the gps (Garmin GPS V) reads 75 MPH.

At 2500 RPM, the speedometer reads 77 MPH - the GPS reads 84 MPH.