I'd like to get on a better tire but the problem is the OEM sizes don't cut it. Tires like the Direzza's, kuhmo xs, RE-11, etc. don't have my exact oem sizes, so plus sizing is a must anyways. The problem is I'd like to keep the rolling diameter pretty similar to stock which I'm finding tough to do.

Wheel sizes: 18x7.5 front 18x8.5 rear
OEM tire sizes: 225/50/18 and 245/45/18


For the front, 235/45/18 is an option for the direzza, xs and re11.
245/45/18 is for the direzza and re11.

For the rear, again 245/45/18, the stock size, works for direzza and re11 but I'd like to plus size it. From here it gets tricky..

255/45 isn't an option
255/40 isn't an option
265/40 only is for re11's
265/35 is the sweet spot and has just about everything available but its rolling diameter is a lot smaller than factory and might be pushing it on a 8.5 wheel width.

Should I just stick with 235/45/18 and 245/45/18 or is there another option I'm missing?

 

Search is your friend........ you will find plenty of options under the below, and it will have the least diameter change on the tire for the speedo. 235/45/18 is too small and will look funny

235/50/18

245/45/18 or 255/45/18

 

Search was done.

235/45/18 was the oem size on the 05 sedan 18" wheels. Are they too small and look funny on them? In addition, 235/50 does not have any available tires I'm after and is not an option.

Why did I already list 255/45/18 as not being an option if someone's going to recommend it? xs, re11 and direzza are not available in that size.

 

why do you want those exact tires? there are plenty of other options out there. the 235/45/18 will look funny on the 07+ and it will probably cause your VSC and Slip lights to come on due to the difference in tire Diameter. if the difference between the rear tire diameter and front tire diameter is greater than 3% your computer will pretty much just shoot itself and give up because it will think that you are constantly losing traction.


Kuhmo has an Axs in the 235/50/18 and it looks like there are about 5 pages to choose from


Tire Rack

 

I autocross in DS and my competition got better tires last week and was .3 seconds faster than me (58.6 to my 58.9). I must now one up him and ditch the RE050's for as aggressive yet still streetable tire as possible.

235 is only 2% off the stock 225/50 size. Provided I don't change the rear's rolling diameter enough to cross that threshold, it should be fine.

 

I must be smoking crack because 235/45/18 isn't available in any of the tires I want. I must have been looking at 235/45/17.

Hell. Now it looks like 245/45/18 all around is my only viable option. The front are going to bulge on the 7.5 wheel.

 

Ah ok that makes more sense. if you are getting pretty serious about the auto cross thing i would think about getting some different rims and then getting a comp tire for them, that way you can have that set for track days. the aftermarket rims would be lighter as well, helping to reduce the unsprung weight. you should be able to get some off of a member selling theirs in the FS section pretty cheap.


the 235 isnt the problem it is the 45 vs the 50 that might cause problems

 

There are quite a few people running that setup without any problems. the bulge isnt that bad but it will most likely make your turn in and handling response worse due to the wider tire

 

To stay in D stock I'd have to have wheels with the same width and offset which is going to be hard to find without getting another set of factory wheels. Just not worth the added expense IMO.

The guys on the local scca boards are telling me my car's problem with pushing could be fixed with a wider front tire so maybe the 245 is the way to go.

I could always say in-line front to rear ratio and go 225/45 and 245/40. Those are available sizes for the tires I want but the overall rolling diameter will be off 3.6% from factory. That's going to throw off the speedo enough to notice as well as change the mechanical advantage...not sure whether for the better or worse.

 

so youre saying its pushing? as in when you turn into the corner you have bad understeer? Tires may help but an adjustable coilover would be ideal. that way you could tighten up the rear to get rid of some of that understeer and make the back end come around a bit giving you better control with the front tires

 

yes, the car understeers in most corners. The only time I can really get the car to rotate is with very hard braking to shift the weight to the front tires.

I cannot stay in DS with coilovers. My only 'tuning' options are a front sway bar, bushings, and tires.

 

then i would definately go with the tires first and if that doesnt help then i would look into that, the Sport sway bar is actually pretty big stock. i think stillen makes one too.

 

I thought I read stillen's was crap but could be mistaken. At this point, tires is probably all I'll do.

 

Stillen, Nismo, Cusco, and Hotchkis to name a few, makes sway bar sets for the G35s/37s.

 

shows you how much i have looked into it.... do a search, i bet you will come up with something.


do they allow strut tower bars or any kind of bracing? i hear G-spec has a pretty good tower bar.