[need help] Calcualte Speed given gear and rpm.

I would like to calculate my GTI's speed given the gear and rpm.
I found the gear ratio as below but seems like something is missing.
ok here is my Math:

1st Gear ratio: 3.36
at 6000rpm
Tire: 225/40/R18

Tire Diameter: 18" + (40/10/2.54)x2 = 21.15" or 0.5372m
One rotation: 2xr*pi = 3.1415926 * 0.5372 = 1.6877m
at 6000rpm 1st gear: (1.6877*6000)/3.36 * 60 = 180.825kmp or 113mph

It is not possible to reach 113mph at 1st gear. :mad0259:
Seems like something is missing. Can anyone help? Thanks

http://www.vw.com/en/models/gti/tri...or.html#/tab=e991431688097d37258cb3a6c7426d58
1st Gear 3.36
2nd Gear 2.09
3rd Gear 1.47
4th Gear 1.10
5th Gear 1.11
6th Gear 0.93

so I missed the rear gear ratio? where to find out the ratio for 2011 GTI?

You're not factoring in the final drive.

divide that by 3.94 or 3.09 and you'll be right on. I'm not sure what the two final drives mean. Its its a dual output shaft tranny or those are for DSG or DSG/Manual, etc.

Thanks TXBDan, you are right. just found out that 3.94 axle ratio for 1st - 4th gear.
3.09 for 5th - 6th gear. it makes sense as from 4th to 5th gear ratio are very close.

Someone posted this a week or two ago. I take no credit for it.