is my fuel pump buggered???

[WINDSCREENGUY]

my van feels faster when i have a full tank of diesel, and it used to do 90mph but now only does 80 mph would it have anything to do with the 16" alloys????

[Valsheda]

I KNOW THIS IS PROBABLY NO HELP AT ALL BUT WHEN I PUT MY 16" RIMS ON WITH 205 TYRES , I DIDNT NOTICE ANY DIFFERENCE , ALSO WEITHER YOU HAVE DIESEL OR PETROL WHEN YOU FILL UP WITH FRESH FUEL IT ALWAYS SEEMS TO RUN BETTER

[transitgeoff]

noticed my mk6 used to struggle to hit 90 now ive put the mk6 16 inch wheels on it struggles to hit 75

[MrMPuk]

It all comes down to what size tyres you have fitted on the wheels, you could of course fit tyres with the same circumfrance as the old ones on the new wheels. Try this one quite a handy tool http://www.miata.net/garage/tirecalc.html

I know when I fitted mine it seemed like the van had got slower as the speedo would only go up to 75 now instead of 85 but using the GPS speed camera detector it appeared that the speedo was now spot-on for speed as it was reading 10 MPH fast before.

[Valsheda]

THIS IS THE DIFFERENCE BETWEEN MY OLD STANDARD TOURNEO ALLOYS TYRES TO THE TYRES ON MY NEW ALLOYS

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
195/70-15 5.4in 12.9in 25.7in 80.9in 783 0.0%
205/65-16 5.2in 13.2in 26.5in 83.2in 761 2.9%