this doesn't hold true at higher speeds due to tire slippage and various phenomenon at higher speeds. Even if your tires were OEM diameter, the accuracy will plummet at 100mph+

 

IBTD list:

1. klubbheads
2. express705
3. CruisnGcoupe
4.
5.

I need two more to make it a fair deletion.

 

why delete? seems like there's some good info that salvaged the thread

 

So what would be an "accurate" way to check the speed of an object that is moving 100mph+?

 

With a radar gun at those speeds, what I was saying is to not extrapolate a radar reading at 40mph to your speed at 150mph. The best way to determine the accuracy would be to due multiple runs at a range of speeds with 4-5 repeats per speed, and then you could determine a relatively good fit to the data which you could then calibrate your speedometer to

 

my speedo never reads fast enough

Faster, faster, faster!