Possible VCU malfunction ?

Hello all,

Unfortunately whilst camping in Wales I got 2 side wall punctures, after being recovered to a tyre fitting specialist garage and after a 2 day wait for the new tyres I was on the road again.
But only for a couple of miles when I noticed a burning smell like I have never noticed before definately not clutch,oil, brake ect and then I started to loose traction through corners and the car wanted to slow itself and struggled to get to 30 mph, then came a loud knocking from underneath and I had to pull over in a safe spot. After calling recovery again, the guy who came out was not a mech but was happy that the car couldnt get me home and recovered me to liverpool.
On closer inspection of my car and I know I should have checked at the garage but my back tyres and spare the origional 225/55zr17 but my new front tyres are doublestar 225/45zr17 and I have a reciept for matador MP45 225/55-17.
Have I been had and could the different size tyres have caused my VCU to malfunction and overheat?

Thanks for any replys oh and its an 03 freelander serengetti

Jim.

First thing ,remove the prop shaft,taking care not to damage the front prop cv gaiter.You should be ok with smaller tyres on the front(maybe not that much smaller).If removing the prop gets you motoring again phone the tyre place in Wales and see if they can sort you out without having to drive all the way back there.

5.5in difference in tyre circumference which = a difference of 54 revolutions /mile. The VCU has not malfunctioned it's attempted to do it's job but cannot slip fast enough and so the transmission winds up. The knocking may well turn out to be a knackered IRD or rear diff.
Wrong size tyres are to blame, its a well known fact. You have paperwork to back you up that the tyre fitter used the wrong tyres so claim from them.

I think Chaser is right, a 10% difference in tyre profile is way to much for the VCU to handle.