I have a stock 2004 G35 Coupe with 35000 miles and i'm about to replace my stock pilots. I getting tires from a family friend and she recommends I put 245-40-18 on the front instead of the stock 225-45-18. Is this a good idea or will this effect my car's handling and performance? Also what are the biggest size tires that you can place on the front and rear keeping with the stock 18inch rims?
I was also wondering if any would recommend the 30,000 mile service from Infiniti or is it just a waste of money? They are charging around $500.
I would appreciate any help.
Thanks,

 

245/40/18's on the front is a great idea. They are easier to find then the stock 225/45s, are the same hight, look better, and will make your coupe more neutral handling. In the back, on your 8" wide wheels, I would put 255/45/18. Almost the same height as the stock 245/45s. They'll look better than the stockers, and will give you a bit more traction in back.

Lou

 

I heard that putting on 245-40-18 will improve handling and performance but that it is a thinner side wall and if i hit a pot hole I could blow the sidewall and or bend the rim. Is that True? Could you fit a 245-45-18 in the front?

 

^^^^^Yes to the first question and No to the second. If your afraid of potholes, drop down to 17" wheels (said with my tongue in my cheek). As I said above, the tire height (sidewall height) between a 245/40/18 and a 225/45/18 is about the same. The outer diameter of a 245/45/18 in front would be about 1" too tall and would upset the electronics. Try to maintain factory diameters.

Lou

 

245/40/18 up front works perfectly on the stock 18" rims. I have that setup on my car... 245/40/18 up front and the stock size 245/45/18 in rear.

The sidewall is almost the same size on the wider 245/40/18 vs the OEM 225/45/18 tires. The aspect ratio of a tire is exactly what it says it is.... a ratio. It's a ratio of the tire's sidewall height relative to the tires width(so for a 245/40 tire, you can calculate the sidewall height by multiplying 245mm by .40 to get your sidewall height in millimeters). As you increase your tire width, you have to decrease the aspect ratio in order to yield almost the same measured sidewall height, which is around 100MM or so on our cars.

In terms of sidwall issues and problems with rim damage as a result of hitting road anomalies... All you need to worry about is making sure the overall tire diameter is close to stock size when going to a wider tire on our cars... the rest will take care of itself.

Oh.. one more thing to consider with the wider tires on the front is that you might get ever-so-slightly faster wear/cupping on the inner edge of your tires. The only way to fix this on an '03/04 Coupe is to get one of the aftermarket camber/allignment kits, beecause our cars don't have adjustable camber at all when in stock form. The accelerated wear won't be anywhere near as bad as it would be with a suspension drop though... and chances are that you'll just get the typical inner edge tire cupping and front end rumbling 2 or 3 thousand miles sooner than you would have with the 225mm width tires. I don't have an adjustable camber kit on my car, but I'm considering getting one soon.

 

35,000 miles on the original tires? That's really something. As far as the 30,000 mile service goes, I would change your oil and call it a day. A total waste of money.

 

Tires are expensive.

i got 20" Maas Rims, tires alone are Mad Gawp for each, not including, mount, balance, tax, and bullcrap...

 

I think there are only 3 or so camber kits out there for our car. I'm not an expert in this area... so I could be wrong, but the 2 main ones I know of are SPC and Stillen as the most popular ones and Eibach also makes them, but I haven't been able to really track down anyone who sells the front camber kits by Eibach.

If I remember correctly, I think one or 2 people may have had problems in the past few years with the SPC ones breaking for no apparent reason at the welds. Don't quote me on that though.

If you get a camber kit, expect to pay a premium for them... they're by no means cheap.... but in the long run, if it saves you even one set of tires, they will probably just about pay for themselves.