15 inch qheels revcounter

[Z4MCSL]

I'm sure this must have come up before but can't find it.

Just fitted 15inch OZ wheels, very very happy with them, car feels great.

I noticed the revs now go way beyond recline...guessing its due to going from 16 to 15?

Will check the speed vs GPS to see if that has been affected too.

I assume this is what's happening right? If not I'm gonna have to reign it I!

 

[Coops Mk1]

Usually with tyre profile change too the actual difference in rolling radius is negligible

 

[Crybert]

I'm sure this must have come up before but can't find it.

Just fitted 15inch OZ wheels, very very happy with them, car feels great.

I noticed the revs now go way beyond recline...guessing its due to going from 16 to 15?

Will check the speed vs GPS to see if that has been affected too.

I assume this is what's happening right? If not I'm gonna have to reign it I!

There’s a difference between going into the redline and hitting the limiter..

as above the difference is tiny in reality

 

[NorthloopCup]

There’s a few calculators online that will give you a definitive answer.

I used one when I geared my cup for the Nordschliefe. Swapped out the 5th gear for a meg 5th and went up from 15’s to 16’s. End result was 153/154 (on the limiter) iirc on the straight running down to Schwedenkreuz.

I’ll see if I can find the one I used.

 

[Adey.]

Pretty sure revs on the dash is taken from engine speed and nothing to do with wheel speed at all on these. Wheel speed on the dash is adjustable within a few parameters for different size wheels and tyres via clip.

 

[VenomUK]

I would have thought speed would have been out not revs?

 

[banhama]

I would have thought speed would have been out not revs?

As above I can see why vehicle speed might be out, but can't understand why the max rpm would be higher.
I guess it's a 182 going from16 to 15", so engine speed measured by the 'thingy on top of the flywheel', and vehicle speed comes from the ABS sensors?

I do understand you would get to max rpm quicker with a smaller rolling diameter, but will that actually increase the max RPM?

 

[Louis]

75 on cruise is 71 on gps with 15inch wheels and 195/50/15 tyres fyi

 

[Adey.]

no, max revs do not change, speedo does change with a rolling radius change.

the dash can be calibrated for certain sizes of wheel/tyre using can clip but its not ever that accurate tbh