Quote:
Originally Posted by tofufi
Dave,
The difference in the (rolling circumference of the) two tyre sizes XCR quotes should be about 1%. Pretty much negligable on a speedometer reading. It'll hardly make the speedometer read 55mph when going 70mph unless something was seriously out before.
You'd see as much of a difference going from a worn set of tyres to a new set.
Surprised you say Volvo speedometers are optimistic, mine reads 70 when the sat-nav reads 68. With standard 15" alloys.  |
You're lucky then Jim, out of the 4 7xx i've owned, all 4 have been wildly optimistic and my current 760 when i first got it with (admittedly worn) 185/60/15s showed about 70 when doing about 55mph.
Going up to 195/65/15 has corrected it somewhat, now giving about 64mph at an indicated 70mph, to correct it completely i think i'd have to go to 205/70/15 which is tempting in terms of ride compliance but not so tempting on the handling front.
