MPH WITH DIFFERENT WHEELS AND TYRES

[Gunslinger]

I remember seeing a thread some time ago, but cant find it now, that showed how to calculate the % diiference in speedo readings when different size wheels and tyres have been fitted.
Can anyone help?

[steve8090]

http://www.alloywheels.com/tyrecalc.asp" onclick="window.open(this.href);return false;

[Gunslinger]

Thanks Steve, thats the one.
Now who can tell me the size of the standard wheel and tyre, particularly the profile. I know its a 14" wheel

Thank you

[steve8090]

185 70

[Gunslinger]

Thanks again Steve

[andisnewsyncro]

185 70

I always believed if the tyre didn't specify a profile like 185R14, it was an 80 or even 82 ?

[Red Westie]

Technically it's 82 but they don't bother actually including this figure in the tyre markings as it is regarded as being standard.
Don't forget that all mechanical speedo's read approx 10% too high to keep drivers in the safe zone and to compensate for tyre wear etc. So typically a speedo reading of 44mph is about 40mph with an accurate Sat Nav.
Martin

[andisnewsyncro]

I moved up to 195R15 from 185R14 which is about 6.4% increase and my speedo is now pretty much bang on with the sat nav reading at 50, 70 & 100 k/ph if that's any help at all

[Gunslinger]

I wonder if my sat nav records my MPH

[lloyd]

Stock tires are 185 x 82, and yes, satnav should give mph depending on setting you are using in it.