does it really matter that much if the tires that we took off of our 2012 Hyundai Elantra were rated as H and we replaced the H rated tire with a T rated tire.

oh I forgot that important part, We the slick winter roads and the OEM tires we had on the car we had 38,000 and the traction or lack of was the reason for replacement, the (H) rated tires were not available but the (T) rating were so we put them on?? I trust the speed ratings are important but doubt we will be going the 118 mph as rated on the T anymore than we would be doing the 130 mph of the H rated tires

yes all four were installed. I was unsure if we put two on the front and the two best used ones on the back if that would maybe create a spin kind of issue. So thank you so much for your help.

Changing the tire rating does make a difference. The overall performance of the vehicle with change fuel consumption, pick up, horsepower etc...

I did the same and driving normal the differences are negligible. Marty