QUOTE(fix24311 @ Apr 2 2013, 10:59 PM)
it means the tyre width is 175mm
the height of the tyre wall is 65% of your tyre width
and the rim fit for the tyre is 14inch
*all legend2 here feel free to correct me*
stray from the spec size and your speedometer reading won't be correct. say u read it 80km/h, but ur actual cruising speed is 120km/h (just an example of course

)
but who cares, right? bigger rim are a beauty to look at

Lol...this argument had been around for so long

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No matter what size of tyres you use, you speedometer is always correct la. Its just that when you compare to the actual speed (maybe speed trap for example), yours is not accurate anymore. That is why recalibration is important
but not many people can do or do it .
Example" More than 4% upgrade, your speedometer will show about 4% different compare to stock tyres and actual world. But you car speedometer is still showing your correct car's speed(unless recalibration done after changes) as it generate the reading from gearbox or drive shaft rotation
The changes in tyres diameter affect the speedometer reading due to rev per miles different but no matter what, the speedometer reading generated always follow your car's speed which may not tally with real world speed.