Hi All,

I've recently purchased an Australian delivered 1968 Pontiac Parisienne, RHD, 327 Chev, 4 door hardtop. I would like to run 15x10 inch rims on the rear with 275x60x15 tyres. Does anyone know what backspacing on the rims I need? Would it be 4.5 inches or 5.5 inches? I've been told that the 68 Parisiennes have the same chassis, brakes, suspension, driveline and diff as the 68 Australian delivered Chev Impala's is this the case? Does anyone here have a 68 Impala with 15x10 inch rims? If so what combo are you guys running?
What is the largest tyre (width wise) that can be mounted on a 15x8 inch rim?
Cheers.

As far as the backspacing for the wheels is concerned, I can't help you but, the Pontiac Parisienne and Chevrolet Impala are the same car under the sheet metal.  

The Aussie delivered Parisiennes and Impalas are both sourced from Canada.  The situation in Canada back in the '60's was different than that in the USA.

In the US, the full size Pontiac was the Catalina.  There was no Parisienne model in the US until the late '70's.  It was an entirely different car to the Chev Impala - even the bolt pattern of the wheels was different.

In Canada, whilst the sheet metal was different between the Chev and the Pontiac, all the mechanical, chassis etc were the same.

HOWEVER (whilst I'm pretty sure this doesn't apply in your case), the shape of the sheet metal on the rear mudguards can affect the size of wheel you can fit on Parisiennes and Impalas of the same year model.  From memory, you can fit a bigger rear wheel on a '63 Parisienne/Laurentian that you can on an Impala/Bel Air of the same year.

Thanks for the info bonnevista, regards..............Steya