Wheel centre bore diameter

[Craig C]

Hi,

I'm trying to get a definitive answer to the question of the wheel centre bore diameter for a tr7/8. There seems to be a couple of options floating around the interweb:

56.6mm (2.225") and

57.1mm (2.25")

The latter is definitely the bore for a SD1 and the former for Spitfires, MGF etc.

I would have gone with 56.6mm but a number of posts on this and other forums suggest that MGF alloys fitted to a TR7 have required MUCH force or a thin spacer to allow them to sit flush against the face of the hub, suggesting the bore (at least close to the hub) is in fact 57.1mm. But if you have a wheel with a bore or 57.1mm will it "rattle" around as most of the bore is 56.6mm, suggesting that a wheel should have the 56.6mm bore but add a small bevel on the edge?

I can't get a set of calipers into the wheel bore of a standard alloy that have in the workshop and a ruler just aint that accurate...

Anyone know definitively?

Craig
Tr7V8

[ColoradoTR8]

When I had apaters made for my TR8 I measured the hub centers to be 56.7mm and the original alloy wheels to have a center bore of 56.8mm. I had the adapters made with a 56.8mm centerbore and they snugged right up just like the original alloys did.

Your best answer may be to measure the centering hubs on your car to know for sure.

<b><i>Shawn</i></b>

[Stag76]

I fitted Honda discs to mine that had to have the centre hole bored. The hub size was 56.6mm

TR7 Convertible
Sprint Motor
MegaSquirt EFI

[Roger27TBB]

hello all ,
last week i got a new set of factory alloys from rimmerbros.co.uk. I assumed that they
will fit on the hubs but to be sure i took one and tried to put it on the front hub.
I didn`t measure the hub before.
Result: It doesn`t fit. On the package was a sign with the measurements. I should
better have read this before trying. The measure of the bore was written with 56.5mm. I measured 56.75mm at the front and rear hub.
I have an old factory alloy bought on ebay before and that fits.
So i try to complain this, because i won`t damage the new alloys paint with drilling
or milling.

regards

Roger

[prackers]

Not sure if this helps as I have no idea of the bore but I run 15" MGF wheels on both my TR's and both fit snuggly with no play at all, with or without spacers, front and back. I just treated the SBC convertible to a new (to me) set last week.