I have been running my 957 on the standard 18" wheels (255/55/18) with 20mm spacers to give a better stance but at the weekend I will be changing to 20" wheels (genuine Porsche) which I just bagged on eBay. The new wheels have 275/40/20 rubber fitted and I wonder if I should still use the spacers or if they might be too much.
Any opinions guys?

 

Yes. The cars look goofy and top heavy when the fenders hang over too much. Also, when you upgrade the tires, get 275/45 r20 rubber. You will thank me later.

 

I am going to leave my 20mm spacers on when I put my summer wheels on in a few weeks.

 

And if you can run staggered 20 inch rims then go for the 315s in the rear. It is an awesome look with 10mm spacers up front and then no need for spacers in the back with those fat rear tires. Its what I have on my 05 Turbo with factory staggered Sport Technos

 

I think 315s are pretty far I outside the recommended section width for a 10" wide wheel. I run those on my 12" wide wheel and 997 GT3s run a 305 on a 12" wide wheel.

 

Did exactly that - 275/45/R20 tyres and 20mm spacers. The ride quality is surprisingly good with the extra few mm of rubber under me and the stance is now perfect!! So thankyou

 

You are welcome. Glad it worked out. It is actually about .5 inch of extra sidewall which equates to just under 4% larger circumference. They fill the wheel wells so much better and ride so much better that I will never go back to the 275/40's on this vehicle.