I have a p215 and 3 225's on my car.

Can I replace all with the 215's?

I don't really plan on taking 90mph curves.

TIA

Yes as long as you get the aspect ratio (the middle number such as 60 or 65) correct. You want to keep the diameter of the tire the same to keep the speedometer readings accurate.

Here's a tire size calculator to compare sizes.

Tire size calculator

Awesome!! Thanks!!