Would 215/45-17 fit on the stock rims with the stock tire size being 205/50-17? On an '06 3s HB.

 

Yes, they will fit. I run 225's on my rims and they are 215's stock.

 

going above 205 will throw off your speedo as the ecu is not calibrated for it, im running with 215's and my speedo reads about 5mph faster than actual

 

doesn't the 205 of the stock tires refer to the width? how would having only a wider tire throw off the speedometer? you'd need a larger profile (the 50 of the stock tires) or bigger than 17. stock tires are 205/50 r17.

 

Moving to 205 section width tires will NOT (in and of itself) alter how your speedometer and odometer register your speed and distance.

 

Yes and no. Width, sidewall height and wheel diameter can all be changed without affecting the speedometer. That said, when one of the above measurements is changed, at least one other must change as well to keep the outer diameter of the tire the same. Assuming one is staying with stock 17 inch wheels that were wrapped with 205/50 R17 tires, and assuming said individual wanted to move to say a 225 section width, all he or she would have to do is change to a 45 profile tire (i.e. opt for 225/45 R17 tire size).

Consider the following:
205/50 R17 -- Diameter: 25.1" (Factory size)
215/45 R17 -- Diameter: 24.6" (Too small, the speedo will register a higher speed)
215/50 R17 -- Diameter: 25.5" (Too large, the speedo will register a lower speed)
225/45 R17 -- Diameter: 25.1" (Just right)

 

what he said. the width is based on standardized measurements whereas the height is based on the width. a 215/45 is going to be taller than a 205/45 because it is wider. make sense at all?

 

yep, makes sense. I remember hearing that the profile was some sort of ratio. so if i want 215 width tires, what profile and radius should i go with?

 

See my post above; there really aren't any 215 section width tires made that will work on your car without causing some speedometer and odometer error (errr, unless you want to buy 18" wheels and go with a set of 215/40 R18 tires). Long story short, if you want wider tires then your best bet is to go with a set of 225/45 R17s.