« Reply #8 on: Sep 7, 2005, 11:35AM »
http://www.miata.net/garage/tirecalc.htmlStock size is 195/65R14.
Front tyres - speedo will be 4.2% too slow.
Rear tyres - speedo will be 6.3% too slow. These aren't acceptable figures - when you're doing 100km/h according to your speedo you'll be doing 106.3km/h.
You may be able to get away with it if there is enough wear on the front tyres, but otherwise you'll need to buy new tyres.

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