Which is the best wheel spacer option; Bolts or Studs?

I've searched and although there has been much debate on spacers in general I couldn't specifically find an answer to this question. I want to fit some 15mm (hubcentric) spacers on the rear of my C4, I'm assuming a spacer using longer bolts mounting directly into the steel hub thus sandwiching the spacer between the hub and the wheel is preferable to the alternative style with studs that which bolts onto the hub first with the wheel being separately mounted on a secondary set of studs pressed into the spacer itself? Logically a steel bolt mounting wheel and spacer directly to the steel hub seems the stronger method of mounting the wheel compared to the latter which seems to have the greater potential for fatigue and failure, is this a fair assumption?

I don't know the science but I;ve always gone longer bolts up to 15mm :thumb:

I prefer studs, which make changing wheels easier.

Porsche fitted 17mm spacers as standard to the rear of the 996 turbo when used with the Sport Techno wheels. The spacers bolt to the hub and the wheels fit on studs. I would assume longer bolts would have been cheaper, so in my mind this must be a better way to do it, or Porsche would have gone the cheaper route. MC

I've studded my hubs, then sandwiched the spacer. I think the studs were M14 x 1mm

I agree mounting the wheel is a lot easier with studs, that appeals. I guess it could be quite faffy trying to mount the wheel with a loose spacer in between, or is the hubcentric lip generally deep/tight enough to hold the spacer in position on the hub while you offer up the wheel? Interesting that Porsche used a stud style spacer. Has anyone exprience of the DesignTek bolt on studded spacers , are they well designed and of good quality? There's a crazy range of prices on spacers, these seem quite reasonably priced. I'm an advocate of 'you get what you pay for', but wary of simply paying more on the assumption of receiving better when the difference is just an inflated margin on the part of the vendor! That seems like a good solution. Is it simply hub off, insert studs from the rear then reassemble, or did you need to machine the hubs to countersink the stud head or similar?

The bolted-on wheel spacer will be marginally heavier by virtue of the 5 extra wheel bolts (but only a small increase as you don't then need to run longer main studs/bolts). Porsche would have gone for a mechanically fixed route to prevent spacers going AWOL during wheel/tyre changes and for economies of scale of just producing one length of 996 wheel bolt. As above, I'd happily go up to 15mm for a slip-on spacer, with suitably long aftermarket studs and nuts.

I've always been happy with hub centric spacers up to 15mm.......I've never gone larger than 15mm as to me the wheels are then the wrong offset in the first place but I have seen up to 20mm OEM spacers fitted to OEM setups...... mounting the wheel should not be a problem with hib centric ie thats why you get provided with the wheel mounting pin in the tool kits of cars that use bolts and not nuts to mount wheels :wink: .... .....I've just sourced some OEM 5mm spacers off ebay for my boxster.......interestingly they come supplied with longer hub mounting screws so that they can screw directly into the hub through the disks to ensure they are always lined up with the bolt holes.....I have heard however that you don't really need these as the spacerss "fit like a glove" ie better fit than none OEM hub centric spacers........I'm not sure if wider OEM spacers kits come with longer hub screws or not :dont know:

Just sold a full set of hub centric spacers with extended blots and also locking puzzle studs. They are a straight forward fit on the front, the rear tends to be a bit more awkward as the wheel won't sit on the hub easily when your fitting the studs. They do slightly improve the flatness when cornering, although that may be more down to the DSC module.