tyres

[Martyn]

I have alloys with 185/60/14 tyres on my tzd. I also have a set of brand new 185/70/14s . can I swap them and will they fit? They look a bit big to me. I don't know why there seems to be such a difference. thanks, martyn

[tim leech]

They will fit on the rims but will throw the rolling radius out of kilter and muck up the speedo slightly, if it was me I would replace like for like. 185/60s arent expesnsive, neither are 195/60 14s either which will also fit.

[jeremy]

You can work out the theoretical circumfrence as follows:

Wall height: The 60, 65, 70 etc is the aspect ratio which is the ratio of wall height to tread width - so for a 185/70 tyre the tread width is 185mm and the wall height is 129.5mm (70% of 185mm)

The rim width is expressed in inches which is handy for imperialists like me but confusing here. The conversion is 25.4 mm = 1 inch - so a 14 inch rim is 355.6mm

So tyre diameter is 355.6 + 2x 129.5 - = 614.6mm (or 24.2inches)

and its circumference is pi x diameter (or if like me you haven't a scientific calculator 22/7) = 1931.6mm (or 76 inches)

185/60 - circumference 1815.31mm (or 71.46 inches)

195/60 - circumference 1853.02mm (or 72.95 inches)

[tim leech]

What he says!....

[DavidRutherford]

Martyn... Where are you based? I have a set of 185/60 14's on a 405, which are incorrect for it. They're about 50% worn. The 405 should have 185/65 14's or 185/70 14's on it.

Interested in a swap + some cash for your tyres?

[kiwi]

You know that 10% speedo error you used to be allowed for speeding? Well fit 185/70/14s and say good bye to it

You will find more of those little camera flashes and blue lights appear behind you because your speedo may say correct spped but you will be doing more on increasing your tyres for 60 to 70s.

Spoken from experiance that the speedo error is thrown out by those size tyres.