I have oversized tires, I tested out my speedometer accuracy with a radar gun. It reads 2mph below my actual speed, but according to all of these tire convertor websites, I should be reading 4.1mph slower with 225 65 15 tires, which means my speedometer is off. Now, my question is, if I had stock tires (195 70/14) installed, what would my speedo read? I've been trying to figure it out, but I can't. Help!

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

If your data is accurate, the speedo would be reading 2.1 mph above actual speed with the stock tires.

According to this calculator:

http://www.miata.net/garage/tirecalc.html

with 195/70-14 tires your speedo will read 6.7% faster than it does now. I can't convert that to mph without a reference speed.

Thank you very much.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

With my 255 60 r16's on my 300SD...my speedo reads dead on.

But it is from a car with a different rear end ratio. Worked out nice.

Same here, my 300D was reading high with stock tires, but with 205/70-14s it is right on the money.