Am I just imagining it?

[ogz]

HI Folks

Well excuse me if this is a bit of a dumb question, but, I've just fitted new wheels to my SDI, and I am sure its affected the handling slightly. I can see that the slightly larger diametre has affected the camber of the back wheel so that they are slighty negative (top in, bottom out) and it feels like that is what's doing it. When I'm doing say 50 upwards, and i steer into a corner I get the sensation that the car is settling onto the back wheel slightly but and it makes the thing feel a bit twitchy at the back end. I've just sorted the tracking all round - could a tiny amount of negative camber at the back be affecting the handling like that? Its really not that major and compared with some of the camber set ups you see folk with its really hardly anything. I've only gone from 175/55/R13s to 185/65/R14s so I calculate that that in theory means a change in overall rolling diametre of 31mm ish, which sounds like significant enough to make a difference. When I measure across the wheels it looks more like there is only a difference of more like 10 mm. To preserve the original rolling diametre I figure I would have to gone for 185/50/14s or something like that. anyway i can see that the bigger wheels are affecting the camber, but I can't believe it is doing anything more than adding a few more people into the car.

Also it seems like the alloys (pirelli p-slots) are noisier rolling on the road - might just be the tyres though I suppose?

Whadya reckon?

Edited September 22, 2010 by ogz

[RobG]

My sport came with 185x50x14's, it's currently running 195x45x15's (on bathursts). I did have it on 185x50x15's for a while as that's what the bathursts i got came with, so figured i'd run them down then replace them. The change in diameter affected the speedo reading, so it matched speed with the satnav (normally the satnav reads under your speedo)

With the 65 ratio you've added quite a bit of height on the sidewall, so it's not unfeasible that there's more flex there, and it's causing the wobble.