Tyres and gearing

[westyguesty]

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 ?

[andysimpson]

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

[sixsprings]

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

["WEAZLECHIN"]

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

[toomanytoys]

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...

[HarryMann]

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

for the same Aspect Ratio (AR)