by Manaz » Sun Jul 24, 2016 1:45 pm
Be aware that it's illegal to use spacers on public roads, and if you have an accident and an insurer finds out about them, they CAN be used to invalidate your policy (as they mean the car is not roadworthy, and thus they have an escape clause, irrespective of whether or not the spacers contributes to the accident).
All this said, flat slip-on spacers are bad - as already indicated, they reduce your wheel's ability to stay hub-centric. You really want proper hub-centric spacers, which generally start at between 10mm and 15mm thickness. Of course, they then push your wheels towards your wheel arches, and that brings its own issues. As does the fact that with stock wheel studs, you're losing precious thread for your wheel nuts to hold onto (I've read before that the stock threads are only 3mm longer than absolutely necessary, and if you add spacers that are wider than this, you now no longer have enough thread to adequately tighten your wheel nuts). You're also adding load to your wheel bearings (because you're pushing the load on them wider), and there can be impacts on steering as well though increased scrub radius, etc.
The easiest/safest/least-risky solution may simply be to select more appropriate wheels/tyres.