I've used spacers in the past and I have used both kinds of hubcentric spacers - the kind that bolt to the hub and the kind that sit on the hub and require longer bolts.
I have never had a problem with either kind.
I have not used spacers on the front hubs.
Two reasons for this:
1) From what I remember, it isn't possible to get hubcentric spacers under 5mm
2) Going with a wider spacer (in order to have a hubcentric spacer) would have likely caused rubbing on the front arches.
Also, I have to say that I wouldn't be completely happy with running spacers on the fronts, as these are the turning wheels and exert greater lateral forces across the wheels and hubs.
I have no problem with using spacers on the rears, regardless of which kind they are.
However, it is the general opinion that hubcentric spacers that require longer bolts are better than the kind that bolt to the hub.
Although safe for normal use (not track days etc), the spacers that bolt onto the hub do not offer as much "meat" to secure the spacer to the hub.
The attached picture shows you a worse-case scenario.
Guy had type 2 spacers on the front of his R35.
Enjoyed a track day and noticed something wrong when nipping off to the petrol station after a track session.
Type 2 spacer had literally been pulled off the hub.
This, in my opinion, was due to a few factors...
Extreme cornering forces being placed across the front wheels and hubs - it is an R35 afterall - grip/ cornering capabilities would have magnified the forces on the wheels and hubs.
Heat build-up may well have helped weaken the spacers perhaps.
And also, the "meat" factor that I mentioned before. If you look at the type 2 spacers in person, up close, you will see what I mean.
The bolts, that secure the spacer to the hub, need to sink into the spacer so you can then bolt your wheel to a flat surface. This compromises the amount of meat between the hub and the bolt.
This I think was the main factor in R35 driver's problem.
Proper hubcentric spacers will not move around once in place, as previously mentioned.
Correct spacers that are suitable for your car will fit very snuggly over the hub and there will be no room for movement. They are then bolted firmly into place by the bolts.
Before considering spacers, you should really consider getting wheels with the desired offset or get some wheels made with the offset you want.
If these options aren't possible, then spacers can be considered.
I have used spacers on my old CLK, and briefly on my 63, and had no problems whatsoever.
As for checking torque on the bolts, just check them as you normally would - after a few hndred miles, re-torque them. You don't need to repeatedly check them.
To summarise:
I believe spacers are safe (having used them for years with no issues).
I would be abit apprehensive about running spacers at the front - but if they are thin, you should be ok - although you may not be able to get them hubcentric.
Either type of spacer are fine for the rears, as these are not steering wheels. But type 1 spacers are the favoured type.
) I think they where £50/£60 with the longer bolts
