2015 Ford Fiesta, Tyre Pressure Monitor alerts

Gosh

Hi,

I recently bought a second-handd 2015 Ford Fiesta 1.0L, the Tyre Pressure Monitor system comes on regularly. I've checked tyre pressures and there's no apparent leak.

I did notice that on the rear I have 195/55-R15 tyres and on the front 195/50-R15 tyres (might be the other way round). Checking this online there's a 19mm difference in the diameter of the tyres and I was wondering could this be causing the Alerts and secondly will this difference have any other impacts.

The tyres look fairly new.

Thanks for any advice

colm_mcm

They should all the the same size.
The newer TPMS systems compare the revolutions of the wheel to check if there is a discrepancy.

Having different size wheels front to rear will affect things like headlamp levelling, and it could be argued that the car won’t drive as intended.
If you bought the car from a garage, bring it back and get matching sizes all round. Get them to then readjust the the headlight beam as it may have been changed to pass an NCT.

Gosh

Should the different tyre sizes have been picked up during an NCT test?

colm_mcm

No, as long as the tyres on each axle match there won’t realistically be a fail.

OldmanMondeo

We have a Kuga with the TPMS, when it come on, just check the tyre pressure once all tyres are at correct pressure, just reset the system, should be done from the drivers menu.