speedo out

[The 3Ts]

Hi all i wondered if anyone could give my any ideas as to why my speedo is reading more miles than it should be appox 5mph out
i have the right size tyres 205/65/15 all around so i dont think it is that
Is there anything else that could cause this problem
thanks tony

[bigdaddycain]

5MPH out which way? Most speedo's are designed to over read a certain percentage...

[francophile1947]

Your tyres are smaller than the standard 215/65x15.

[westonwarrior]

loads of bongos are out a bit. not sure why

[The 3Ts]

what size tyre are you running on

[Northern Bongolow]

Your tyres are smaller than the standard 215/65x15.

.
65% of 215 = more than 65% of 205, someone with better maths skills may say the difference is about ??? the difference you have.

[gasace]

Your tyres are smaller than the standard 215/65x15.

.
65% of 215 = more than 65% of 205, someone with better maths skills may say the difference is about ??? the difference you have.

The 215 refers to the width of the tyre, the circumference is the important size that is set by the size of the rim (15) and the tyre profile (65) so they should be as standard

[francophile1947]

The 205/65x15 tyres that you have are 1.97% smaller than the standard 215/65x15 (see http://www.tyresave.co.uk/tyresize.html). Therefore, your speedo will be reading faster than you are actually travelling. Even on 215/65x15, I found that my speedo was slightly faster than actual speed, which is common with most vehicles, and means you don't get done at speed cameras. I now have 225/55x17 fitted and, per the satnav, the speedo is spot on