Do you have base 18' or sports 19' because I believe our 18' base rim can go up to 285, but 275 would be the safest. 245/45 and 275/40 would be perfect for my base 18' I guess :rofl2:

Yes I have the base w touring package which I think has same tires. 18 inch rims in standard base configuration.

Base can take 245 width up front and 275 width out back while staying within the tire manufacturer's specs.

Oops... yea mine are 19s, and they're a little wider than stock sport wheels.

ahhhhhhhhhhhhhhhhhhhhhhh! I wish I had 19'!!!!!!!!!! ahhhhhhhhhhh!!!!!!!!!!!! :)

the thing is I really want fat side walls. I don't plan to drop my car, so maybe I was thinking that if my side walls are fat enough, it looks like that my car has been dropped.

You'll just end up raising the car as you go to a taller sidewall, and at some point it will start to look ridiculous.

Steve is right, I had a friend who had 40 series tires on 18" wheels for his 350Z. WOW it was weird looking.

wait a min, I was planning to get 245/45 and 275/40. so what you are saying is 40 and 45 is too tall? I mean I have stock tires and they are both 45s. I think they look just fine! :)

Use this tool Tire size calculator and come up with the aspect ratios for those tire widths that get as close to the stock height as possible.

Here's another tire/rim calculator you can play with.

Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

Thanks a lot for using your time to kindly post up those calculating tools! :) would you prefer 20mm spacers all around or 20mm front or 15mm rear?

what about the side walls? do you know? Thanks :tiphat:

Stock fronts on the non-sport wheels are 225/50/18, which are 26.9" tall.

For 245, you'll want to run 245/45/18 which is 26.7" tall. The closest you will get to stock height.

For the rears, stock are 245/45/18, which are 26.7" tall.

For 275, you'll want to run 275/40/18 which is also 26.7" tall.

So your original specs were fine. These sizes will be perfect.

Yeah those sizes should be perfect. I switched to the Continental DWS (all season) and got 245/40/18 front and 275/35/18 rear. I think I will switch to the DW summer tires when I need new ones and go with 245/45/18 and 275/40/18. It will be cheaper to install (30 series tires cost a lot more to install than 40 series) and will help with my scraping issues on driveways since my car is lowered.