Well, the 1988 lug nuts have shank diameter of .700"-.702", they fit tight in the wheels. Those Summit lags say shank diameter of .68"

I don't have the exact wheel hub centering stub diameter, but google says 73.8-74.X MM.

Something needs to center the wheels for high speed driving.

Conical lugs will do that of the lug studs are centered. A tight hub/wheel center interface will do that also.

Will .020" diff in lugnut shank diameter make difference on centering if the wheel hub is not almost a press fit onto the nub? I say probably not, though i would have to come up with something to fill the open centers of those summit lugs to be aesthetically pleasing.

Doug

 

AZ Doug
As I understand it, the Jaguar wheels are hub-centric, that is a machined conical male centre on the hub fits precisely into a machined conical female on the wheel itself. These are only about 1/4 inch deep on the rear hubs, but are deeper and more obvious on the fronts, but they do the wheel locating. The washer under the wheelnut is what holds the wheel to the hub, the washer being essential so the nut can clamp the wheel, without that the nuts would not clamp the wheel in place. The precise diameter of the nut tube (within limits, obviously) is not important in the XJS fitment, as long as it properly holds the washer to clamp the wheel.

Rear hub with centric cone marked in blue


Front hub with centric cone marked in blue

I realise loads of cars have wheelnuts that are conical and that locate into conical depressions in the wheel itself. Jaguar XJS wheels are not located in this way.

The nuts come with a black rubber bung to close off the open end, by the way.