How fast does your car go in each gear ?

Well, this is all pretty simple really, but it's interesting anyway. Yes, it's another graph.....

In order to work this out, you use the following expression, which is pretty simple:

or if you prefer km/h it's:

where profile and width are the tyre dimensions, and wheel is the wheel size in inches. Eg for a 165/65-14 tyre, set profile to 65, width to 165, and wheel to 14. Final is the final drive ratio, which is 4.65 on my car, and gear is the gear ratio. Everyone knows what revs is, and....

roughly speaking....

I should get off my arse and write a nice cgi thing to work it all out for you.

Anway, in principle, by checking this out with a power curve, you can work out the optimum revs to change up at, which might not be the red line in every case, although it's more fun that way.

The gear ratios according to my book of all useful knowledge are:

I'm more bored than this dude here, take me back.