These days (& actually for quite a long time!)
ALL OEM Spec vehicle speedos will show a speed that reads somewhat faster than your true speed. By International Agreement, speedos (and the odometers & trip meters etc that use/show miles/km derived from the same tire rotations) are allowed to read faster than true,
but never slower, and that is generally by a 'percentage' - there's more to it, but
basically, there's a maximum allowable variation of
up to about 10%. So yes, your speedo is going to be showing that you're going faster by more mph the faster you go - which, just for clarity's sake, means that at an indicated 10mph, 10% is 1mph, so you
might be going as slow as 9mph; while at an indicated 60mph, 10% = 6mph, so you
might be going as slow as 54mph, or anywhere up to 60mph; or at an indicated 100mph, 10% = 10mph, so you might be only
really doing 90mph, or anywhere between that & 100mph - but if all the rotating things on your vehicle are stock spec, then you almost certainly won't be really doing 105 mph
OR even 100 mph!
And because of the variations in all sorts of things like the way that particular unit was originally calibrated, the tolerances in the accuracy of the manufacture of all the bits involved, minor differences in tire pressure & even the tire's state of wear, no two vehicles, not even two of the same make & model vehicle that rolled off the production line one after the other, are ever likely to have
EXACTLY the same variation, altho they might be pretty close! So the difference on your friend's speedo might not be the same as the difference on yours; but the chances are, unless steps have been taken to try and make either of them read more accurate already, both speedos will be showing a speed that's faster than your truly accurate speed, by anything up to about 10%! And that or possibly a slightly different but no more extreme variation will also likely apply to the number of miles/km your odometer & your trip meters show, but it won't necessarily be exactly the same variation as your speedo, or anyone else's for that matter - they'll probably be close, but not
EXACTLY the same! :lecturef_smilie:
As mentioned by others ^ many Spyder Owners run slightly taller non-OEM spec tires, for all sorts of reasons, and doing that generally improves the accuracy of your speedo somewhat; but be warned, it'll also change (improve) the accuracy on your odo & trip meters, so you won't make any
really significant changes to your fuel economy by running taller tires, not any that'll
actually fit on the rear of your Spyder, anyway!
