Club 80-90 Forums

Just been thinking about what rims and tyres to get increase the gearing a bit after the tdi goes in.
I understand how diameter and profile alters the gearing, but how does tyre width increase gearing (sure i've read it does, and by altering the width in a tyre calculator increases alters gearing). How does a 245 give a higher gearing than a 175 for example if they are both on a 16" rim with the same profile ?

The profile is a percentage of the width so as with increases the tyre height increases.

guest06 wrote:Just been thinking about what rims and tyres to get increase the gearing a bit after the tdi goes in.

just put in your current rear tyre size into this calculator, and your proposed size, and you'll get it showing you a percentage difference in diameter, and therefore gearing

if your current tyres are 185r14, or any other that don't show a profile, then assume that they are 80 profile

http://tyresave.co.uk/tyresiz2.html

a 225/50/14 will rev higher than a 225/70/14 as the width of the tyre is 225mm and the profile is 70 or 50% of the width. so if you increase the profile and the rim diameter you will be altering the gear ratios. great if you have a 1.9d. a well needed alteration

see the other thread too.. depending on what gearbox you have bigger tyres are not the answer... With the effort of TDi ing.. do it right and have the/a box rebiult to suit...

The profile is a percentage of the width so as width increases the tyre height increases.

for the same Aspect Ratio (AR)