I have searched, but couldn't really find if this combination would look alright and actually work. As everyone knows stock on my 06 base is 225/45 and 245/45. I was thinking of maybe going with Nitto 555's in sizes of 235/40 and 255/45, will this look weird? According to the tire calculators height wise they are very similar to stock, they will just be a little wider. What do you guys think?

 

get something other than the nitto 555s, they haven't any good reviews

why drop front to 40 and not the rear, the way you got it is the front will be smaller in diameter than stock and the rear will be just slightly bigger than stock... i'd stick with the same height either both 40 or both 45, leaving it at 45 will be closer to stock

 

235/40 and 255/40 is the Oem +0 plus sizing. I did the oem +0 to my other car and its much better. I might do that to my oem wheels on the Z since the tires are 2 months away from replacement.

I'd say do the Oem plus sizing in the correct tire size and like cubu said, get a better tire like Toyo T1-R or BF Goodrich KDW2.

 

i'll be switching to 245/40/18 front and 275/40/18 rear this summer.

 

^^^ i have some falken 452 in those sizes waiting to be mounted on some nismo 18s... can't wait till monday, i think those sizes are a little too big for factory rims, it would fit but look odd

 

I recommend the OEM width plus 20mm max.

 

I would say Falken Azzeni rt615 in 225/45 and 245/40. That's what I have and they are amazing tires and they look bad ***. They are also only like $160 a piece from edge racing.

 

the bridgestone stock oem 245/45/18 tires are way smaller than my contisportcontacII 255/45/17. i think 275/40/18 will look just perfect.

 

It might just be me, but the problem is there isn't much of a selection in the 45 aspect ratio.

 

I am thinking of keeping the stock sizes and maybe going with Falken FK-452's they seem to be getting pretty good reviews from those that have bought them.

 

I've noticed the same thing...

Was this the general consensus for the larger tires on OEM 18" wheels:

Front: 235/40/18
Rear: 255/40/18

I too am in the market for new tires, first replacement, and am finding a lack of choices in the factory sizes

 

Using the tire caculator (http://www.miata.net/garage/tirecalc.html) in https://my350z.com/forum/showthread.php?t=203755:

Stock Size
225/45/18
225/45/18

Other Size
235/40/18
235/40/18

Change
2.2% smaller diameter
2.4% smaller diamater

 

Here's what I'm looking at when replacing my stock '06 tires (and using my '06 rims):

FRONT: 255/40/18
REAR: 275/40/18

Diameter (tire height) is same as stock and you stay within the 3% rule between the front & rear tires so it doesn't affect your TCS/VDC.