I will be buying new tires in a couple of months and have decided on the Continental DWS. I had them on my previous car (Mazda6 v6) for about 7500 miles before trading for my G37s and really liked them. I need to know what size would be a better fit for ride comfort then handling. The two arrangements would be:
1-235/50ZR18, 1-255/45ZR18
2-235/45ZR18, 2-255/40ZR18
I am leaning towards the second setup as the Conti's are a little softer and the lower profile would help stiffen the sidewall and help the handling but still be a somewhat softer ride. Also according to the Continental data sheet the second setup seems to be a better match to each other. I am a complete novice at this so most of the above is my speculation and therefore need the advice of the experts on here to let me know if I am on the right track or not.
I am going to attach the data sheet so you can see what I have been looking at. Look for the yellow lines in the sheet.

 

I just had tires installed on Friday. I went Cooper Zeon RS3-A 245/45/18. I'm very happy with my selection and they are cheaper than the Conti's. Just my two cents.

 

The contis are great tires. I have 225/50 all around on my sport staggered wheels as my winter setup.

I know the 235/45 are very close in diameter to the 225/50, and as long as the rears are within 3% you should be fine. Going slightly smaller will weigh less but might not fill up the wheel well enough, and vice versa with slightly larger tires.

 

The best size for stock wheels are the stock size: So for the 18" wheels it's a 225/50/18 that tire has a OD of 26.9" the best closest size is 245/45/18 that has an OD 26.7" or a 255/45/18 which has a OD of 27.0" but it's a bit too wide.

Keep in mind that that if you have the Infiniti G37X Sedan AWD 18" the rim is 7.5 inches so going to a wider tire isn't a good idea.. I just did Lexani wheels on my 13 G37x and they are 18x 8" wide so I went with the 245/45/18

Unless you have a RWD 37s which is a staggered fitment: Stock is 225/50/18 front, 245/45/18 rear or if you have a wider wheel you could do 245/45/18 front, 275/40/18 rear

 

Best size is the size written on your owners manual. Or prolly written on the sticker on the inside of your door.

 

Thank you for all your responses, however I need to clarify as to what I am after. I have a 2011 G37s Sedan and I am considering going to a wider tire but don't know what would be the optimum for the stock wheels. I will probably not go to a lower profile as canucklehead mentioned there will be "extra" space in the wheel well. So probably my first option would be the best. (1-235/50ZR18, 1-255/45ZR18)

 

I'm going to jump in here, as well. Our '09 "S" sedan is getting pretty lean in the rear. Not all that happy about the staggered widths, as not being able to rotate is going to kill a good extra 10-15K on the set of tires.

That being said, is the most popular wider option, with stock rims, to go 235 front & 255 rear? No rubbing issues at all with that, right?

However, can I alternatively go 245 all around? Or is that too wide for the stock front rims?

Thanks!

 

Try the calculator at 1010tires.com or the shopping tools at tirerack.com, you can put in a staggered set of tires and see what is available. Once the tires come up you can look at the specs and see the approved rims and outside diameter. Assuming you want to keep speedometer about right and the fronts and rears similar (not sure if the ABS compares front to rear?) your choices will narrow down quickly. Also, not all tire models come in all sizes which narrows the choice further, especially if you don't want a summer-only tire.

 

Sport Sedan 18", I'd go with Michelin Super Sports

 

Taller tires = ride comfort

 

I messed around with the options on Tire Rack, 10/10, and a few others. I never really saw any more options than just the exact factory specs, for 225 front / 245 rear.

 

To Reddobe: The Optimum Size for you Stock Wheels is the stock size.. period. You gain nothing by trying to put different sizes on the stock wheels, in fact you can degrade performance by trying to put tires that are too wide on the stock wheels.. Here are the sizes and how they work out:

235/50/18 od 27.3 Wrong
255/45/18 od 27.0 Wrong

225/50/18 od 26.9 OE size.. correct
245/45/18 od 26.7 OE size.. correct

 

To ErikM Thanks for your input.
The underlying rationale for the larger size is that I "thought" the Continentals did not come in the OEM size, this may not be true, I need to recheck this. Then, based on a post earlier (see attachment) by a DiscountTire rep it sounded like it was OK go slightly bigger and have no adverse effects. So if what he said isn't correct then I need to refocus my search on a different All Season tire that comes in the appropriate sizes.
At my age I'm not looking for the best handling summer tire as I am not going to be pushing the car to it's limits or go drifting. Just want to be safe in all kinds of weather but still want to enjoy a sports sedan. Hope this helps a little more for everyone reading this.
I welcome more input on the brand of tires if in fact the Continentals are not going to be a viable option.

 

the DWS comes in 225/50/18, which is the OE size up front. i know because i have them. the OP is correct that the DWS does not come in 245/45/18.

you will be fine running 255/45 in the rear. those have an OD of 27". the 225/50 in the front are 26.9". so a 0.1" difference, which is no problem at all. the DWS is a great tire so go ahead with your purchase. 225/50 up front and 255/45 in the rear will work just fine.

 

I should mention that I actually sell wheels and tires for a living.. in any case if you really want to do the Conti's going to a 255/45/18 in the back is ok.. 255 is a hair wide but it'll be ok. FWIW Michelin offers the Primacy MXM4 in the correct sizes.. I have those on my G37x and love them.. great reviews on tire rack and I'd agree.. they are quiet, smooth, stick amazingly wet and dry and have a very good treadwear rating, they just don't have a cool looking tread pattern :-)