The aspect ratio is less important than the actual sidewall height when it comes to ease of tire mounting. Your 225/45-17s only have a 4" sidewall. One of my cars uses 195/60-15s, which have a 4.6" sidewall, and those can be tough to mount.
WRONG ! Aspect ratio is just another way of stating side wall height !!
Take the width (225) and multiple by thee aspect ratio which is a percentage (40% or 0.40) 225*0.4=90 which is in millimeters. Convert to inches is 3.5" !!
That is "extreme" !
I finally got some bead holders, which keep the bead down in the low part of the outer rim while you work your way around the tire. These are the ones I got, but there are many different styles.
At least 2 or 3 of those, a GOOD mount/demount tool
(like NoMar) and plenty of lube APPLIED IN THE PROPER LOCATION and it CAN be done. Use rim protectors on alloy rims work CAREFULLY from the back with a protector on the machine so the face of the rim does NOT touch the metal base.
Demounting is all about keeping the bead opposite th area you are working on down in the "drop center".
Mounting low profile tires is usually much easier. Work on grass or a piece of carpet withe the rim face down. Lube the appropriate areas. place the outer face of the tire partial on the rim
(which is face down) and use you body to pop it on making certain the area opposite where you are working is well in the drop center. Bead holders, spoon and rim protector are necessary for the second bead.
With the proper technique, patients, and tools IT CAN BE DONE !