I search but came up with different answers.

I just purchased
17x9 enkei rpf1 with a +45 offset all around.

I'm lowered with coilovers and was wondering if
245/40/17 would be a correct size on the 93 rx7, and a preety big noob on tires so bare with me.

I also read that a 245/45/17 would fit but im just not sure at all. Please thank you in advance.

I would like to purchase some new tires very soon

 

The way to correctly size tires is to look at the overall diameter of the stock tire and try to size your setup to be as close as possible to that overall diameter.

For instance the stock 16" FD tire in a 225/50/16 is about 24.9-25" overall diameter depending on the tire manufacturer.

Go on the tire rack and look at the overall diameter of the 17" tires and if you also went wider with the wheels look at the size wheel that is recommended with the 17" tires you found with 25" overall diameters.
Boom! That's how you do it.

 

Like he said^ I always compare with stock [or other familiar to me] sizes when trying out new wheel/tire sizes and I use this site, a pretty cool comparison tool
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

 

255/40/17 +48 will fit and keep the speedometer essentially unchanged on a slightly lowered car with coilovers. Your 245/40's will make the indicated speed a bit higher than actual. The +45 will be close but probably not an issue with 245's...though it may depend on how much you're lowered.

 

Ya I think the 255/40 will fit, I can always higher the car .
But the 245/40 will also fit. This is a tuff one

 

Well looks like I'm just gonna go with 255/40
All around. I looked at so many threads agian and this is a good set up, I'll just have to raise my car all around but that perfectly fine