I dunno if this piccie really accurately sums up what I was thinking about earlier. basically I was trying to say that although the 16" and 17" tyre we all use on our Fabias have the same width of 205, the 205/40 may have more rubber in contact with the ground, giving more grip under same pressures etc, than the 205/45 due to having less of a corner at the edge (i.e is a lot squarer than the 45) I went and took this piccie of a 45 tyre and 40 tyre side by side, in my garage (just happened to have one of each, ok, actually have 5 40s, and 2 45s) and it seems to show what I was trying to say. Only problem is the 45 here is an illegal one having been used on track and the shoulder has somewhat been "removed" It makes the corner a lot bigger on the 45 I reckon. Any tyre fitters/mechanics think the same thing as me? That a 205/40 should be a "bit" gripper than a 205/45 tyre? (it doesn't happen very often I know)

I thought it went more by brand. On my previous car I had 195 something or other, I needed to replace all 4 so went for a cheaper brand. These had a more rounded shoulder even though they were the same size, and to be honest I didnt like the look of them fitted as I like that square look.

The rounded shoulder will result in only slightly less contact because at the bottom where the road is the tyre will bow slightly causing some of the rounded bit to contact the road.

Hmmm....not sure what you're asking J :confused: .

205/40 and 205/45 should have the same contact patch. The profile will probably make more difference to ride and cornering i.e low profile will probably have a stiffer side wall...depending on brand perhaps.

If tyres "bows out" then either the tyre is under inflated or the tyre is too wide for the rim.

I will also acknowledge that certain brands have a squarer profile than others.

NB: All my usual disclaimers apply.

Would have thought shoulder wear is down to the give in the sidewall rather than the width of the tyre (assuming the tyre is correctly inflated, of course )?

Chris

Edited - I see Ade is quicker than me

Agree that brand can make a difference - I bought a pair of falken ZE502's when I had my Saxo which had a pronounced rounding off at the shoulder, especially when compared to Michelin SX-GTs (which are super tyres imho).

Cheers

Edited - I see Ade is quicker than me

:wave23d: