Wheel Size and Recorded Speed

[blancowesty]

I own a 1990 Westfalia which, when I bought it, had the wheels changed for 16 inch fancy alloys (was told they were from a Mercedes S type - which sounds and looks impressive).

I had the tyres changed for 215/65 R16C. The tyre and wheels are, I think, much bigger than the standard size which leads me to my question. When my speedo , eventually, reads 50 mph am I travelling faster or slower than the 50 mph reading and what would be my accurate speed when the speedo reads 50?

Time to hit the calculator!

Thanks for any response

Blancowesty

[T'Onion]

do you have a sat nav that you could check it with ?

[kevtherev]

I own a 1990 Westfalia which, when I bought it, had the wheels changed for 16 inch fancy alloys (was told they were from a Mercedes S type - which sounds and looks impressive).

I had the tyres changed for 215/65 R16C. The tyre and wheels are, I think, much bigger than the standard size which leads me to my question. When my speedo , eventually, reads 50 mph am I travelling faster or slower than the 50 mph reading and what would be my accurate speed when the speedo reads 50?

Time to hit the calculator!

Thanks for any response

Blancowesty

your tyres are just 32mm bigger in circumference than the standard tyre fitted at the factory
so the speedo is 4.89% wrong ...it will read slower than actual

a 60 profile would have been closer