The Place

If i change from an avon 7.2/20-13 to a yokohama 170/500-13 ( got them for free!) the rolling diameters are different by 8mm or a ride height difference of 4mm.

should i run slightly higher tyre pressure to compensate or at my lowly level will i not even notice, my frame doesnt have ride height adjustment.

any thoughts much appreciated.

4mm wont make much difference. Tyres arent that accurate anyway. Tyre pressures will make more differnce than 4MM though.

Don't go off the claimed height, measure them on the rim and at your pressure. Avon's nominal 20" high tyres vary even on their own table. A ten inch rear on my rim is only 488mm rather than 508. The 7.2 front is about 515. The Yokohamas aren't always 500 either. I found enough difference to make the front twitchy when I went from Avon to Yokohama so I raised my ride height. The previous owner used to run Dunlops that are no longer available, but they were 490, so an even bigger jump when I went to Avon.

Jeff

low profile yoko recomended pressure 12psi . this tyre will turn into corner quicker because it is what it says a low profile not as much fold when you turn in , it will also hold the line alot better just ask any f2 rider, unfortunately no longer made