The Mégane II Owners' Club

I've already posted something about this in my introduction, but thought i'd also put it here and hope i get an answer.

My 2005 Renault Megane Dynamique 1.6 16V (Manual / Petrol) doesn't show the true speed on the speedo. It''s about 10mph out. If i'm doing 39mph on the speedo and i look on my sat-nav or go by one of those street side speed checkers, i'm actually only doing 30mph on the road. The same thing at 50mph on the speedo clock is actually 40mph and the same thing on the motorway, when i'm doing about 80mph on the speedo clock, i'm actually doing 70mph on the road.

The car probably has the wrong wheels on it. It's got 16 inch alloy wheels on at the moment and 205, 55, 16 tyres on it. I bought the car second hand, so i don't have any other wheels.

Is it possible to either put low profile tyres on it ? or get the speedo recalibrated somehow ? Which would be the cheaper way of getting a closer reading from the speedo ?

I'm sort of ok driving and knowing the speeds are wrong, but it would be much better if i could rely on the instruments in front of me.

Hi, its generally accepted that all speedos tend to be "optimistic" with their readings but yours is not a normal case. I would expect an error of between 5% possibly up to 10% absolute maximum. If you had a 10% error, you would be 10mph out at 100mph but only 3mph out at 30mph. If you did have the wrong size wheels, that is the type of error you would expect. You are reporting a "zero offset" (fixed) error of 10mph irrespective of the cars speed. If that is the case, I can only assume a problem with the speedo itself. Perhaps it has been apart and the pointer not aligned correctly?

The speedo on my 1.9dci cc reads 5mph above what my satnav reports on all speed, so if you have the wrong size wheels and tyres that may account for the extra high reading

The clock on the car at stand still shows under zero, but i suppose i should really look at the clock speed and sat-nav speed at lower speeds to see where they are, driving at 10mph. I think i'm going to have to give it a few weeks to get some money together and take it to the garage and get it looked at by a professional who can actually drive the car to see what's going on. It is odd that the clock is ten miles per hour out at whatever speed i drive at though.

BTW it's a six month old TomTom sat-nav that was brilliant on my old car.

Just remembered another question... Will the speedo put my mileage out ?

With the can clip you can tell the car what size tyres are fitted for the ABS that may recalibrate the speedo
Just an idea
Steve

Hmmm, i've no idea what a can clip is. Is it a DIY thing or a garage thing ?