Can I fit 17s with 235/45r17s on a 940

 

The tires will fit - although the +2 size would be 225/45-17s. The question really is what rims? My go to resource for rims/tire options is wheel-size.com which shows 225/45-17 on a 7.5 inch ET18 rim was a factory option. If you have the tires already then since they are slightly taller, you'll get about a 1-2% difference in the speedo due to the larger rolling circumference.

 

willtheyfit.com can give you a nice visual of the change in wheel size and lets you tinker a little bit