.245/45 only works on a 7.5" rim because of the larger sidewall. when you drop to a 40 series sidewall, the minimum width goes up to 8" minimum. it would be wise to stick with 8" as a minimum for a 245/45 as well. its still going to squeezed on there. you would really only run that for certain autocross classes.
youre losing traction because youre using a narrow ass all season tire on a 3800lb car with a lot of torque. a 245 all season isnt going to be any better. a uhp tire will be slightly better but youre not going to be hooking with ANY...i repeat...ANY tire short of a drag radial on a rwd Q50 on the street from a dig.
save up for wider wheels and tires, preferably something with 200tw or less if youre serious about hooking up at low speeds.
I've had 245/45 on two of my car's, they were great, and the Firehawk's 500 as far as I am concerned work well, I have them on now..
I tried to avoid the wheels upgrade because I want to keep the car looking stock as much as possible. I prefer the stock look and also see too many Q50s and G37s getting pulled over in my area daily, I want to keep “low profile”.
I was hoping I will be able to upgrade tires with current wheels and improve traction. But it seems like if I want anything above 225 it would be better to change wheels…