Engine RPM and road speed

I've recently fitted an old Smiths tachometer in the Type 3.
Does anyone know of tables that exist to give an indication of engine RPM and corresponding speed?
Currently the tacho reads about 2700 rpm @ 50 mph in 4th gear, running on standard rims (15 in) and tyres. Does that rpm sound right?

Not sure if this would help?

Its a type 2 though...

http://www.type2.com/library/misc/calcspd.htm

hpnotch wrote:I've recently fitted an old Smiths tachometer in the Type 3.
Does anyone know of tables that exist to give an indication of engine RPM and corresponding speed?
Currently the tacho reads about 2700 rpm @ 50 mph in 4th gear, running on standard rims (15 in) and tyres. Does that rpm sound right?

Somewhere in the distant past I seem to remember that a Type 3 with a diff ratio of 4.125 : 1 and the standard Type 3 gearbox the top gear road speed was around 19.8 mph/1000 rpm.

Thanks for the replies -based on that info 26/700 rpm @ 50 seems about right then

1500S wrote:

hpnotch wrote:I've recently fitted an old Smiths tachometer in the Type 3.
Does anyone know of tables that exist to give an indication of engine RPM and corresponding speed?
Currently the tacho reads about 2700 rpm @ 50 mph in 4th gear, running on standard rims (15 in) and tyres. Does that rpm sound right?

Somewhere in the distant past I seem to remember that a Type 3 with a diff ratio of 4.125 : 1 and the standard Type 3 gearbox the top gear road speed was around 19.8 mph/1000 rpm.

My Ghia runs close to 20mph per thousand.

There's heaps of calculators on the interwebs. First one on Google:

http://www.osella.com.au/gear-ratios.htm

You just need to know some of the stats of your car (tyre size, gear ratios, etc)

For the mathematically inclinded you can create a spreadsheet yourself.

From memory Phil had an article in the ClubVW magazine that outlined the formula. Also, Daimo once shared a spreadsheet he had which graphed road speed at various rpm in each gear.

PM me and I'll send you the one I created.

What year Type 3?
3.875 or 4.125 ring and pinion?
What tyres radial or crossply?

3.875 running 165 80 r15 tyres - 2560 rpm
4.125 running 165 80 r15 tyres - 2730 rpm

3.875 running 560 15 tyres - 2527 rpm
4.125 running 560 15 tyres - 2690 rpm

Cheers - its a Jan'71 - 4.125 according to the manual.
I'll check the tyre size on the weekend.
I bought this tacho in a run down state through ebay and patched it up to look OK - but I wasn't sure of it's accuracy.
However the tacho is reading somewhere around the 2600/2700 mark @50 mph - so I'm happy to think its operating fine.
Thanks for all the replies.
Just as an aside - and not that I have any desire to get to it - what would be the redline mark on these motors?