I want to be phat so i spent tax return on rims, how to tell wife?

My ride is a 1996 Dodge stratus that doesn't run. We got our tax money and were going to use it to help buy some things our three year old child needs, she is "special needs" basically.
I saw some rims on ebay I wanted though that costs about the same as our tax check so I bought them on impulse.

I am worried about how my wife will react. Once the rims are on the car, should I act excited and hope she follows suit?
I know our child needs things but I was not able to pass up them phat rims. It will look awesome when the car actually runs.
What should I tell her?