ABS

Okay, here's the deal. I needed to confirm unequivocally that a 245/40/18 with a 45 offset and an 8" rim would fit my 5th gen. I was worried about the inside of the tire rubbing on the strut and I needed to determine if I had to get hub/wheel spacers or not. My gut told me it would fit, but the last thing I wanted to have happen was to mount my tires on my new rims the install them only to discover they were rubbing. For your reference, I am using OZ Superleggera rims and Falken GR Beta tires. My car is also lowered on H&R springs with GR2 struts up front and KONI struts in back set to the upper perch. To determine the fitment, I took some measurements. Here are the results:

General Measurements
Rim width (outside to outside) = 9 inch
Tire width (outside to outside at point of max width on sidewall) = 10 inch

Front
Inside edge of mounted rim to strut = 1 and 1/16th inch

Rear
Inside edge of mounted rim to spring = 1.25 inch

Conclusions

1. Front "should" fit: With the 9" rim mounted, I still have more than an inch of space available (17/16 inch), but the extra width of the tire will be split between the inner and outer edges of the rim. I expect this to add .5 inches of width on the each side of the rim. In theory, this should leave exactly 9/16 inch space between tire and strut after mounting. The effect of air pressure in the tire is unknown at this time. It is possible that air could cause the side wall to bulge slightly, but the rim could also pull the side wall in slighly. Regardless, I doubt the change would be greater than 9/16 inch. What is still unknown is the clearance between the edge of the tire and the inside of the engine bay when the wheel is turned.

2. Rear "should" fit: Based upon the logic above for the front tire, the same "should" hold true for the rear, but with an additional 3/16 inch of space available between the spring and the tire.

If anyone has any additional information or comments on this topic, please let me know ASAP. Thanks!

limsandy

iTrader: (1)

No rubbing.


~limsandy

uscav8r

I'm curious to see what you think of the ride stiffness going from a 50 series to a 40 series tire with the springs.

Good luck with everything.

ABS

Well, I was able to get the wheels setup this past friday. I haven't driven that much yet, but my first impressions are very positive. Control around turns is far better now than before. In terms of overall ride quality, I am getting a bit more road feel, but it's not bad at all. My experience so far has been that the struts make a much bigger difference in the way the car absorbs bumps than anything else. I would say that the car is a livelier with the new wheels, but I think it is in part due to a greater sense of oversteer as compared to the taller side wall. I hope this helps . . . Oh, by the way (and you probably know this already), the sidewall height is a function of both the tread width and the profile . . .

limsandy

iTrader: (1)

So, uh..... any rubbing?


~limsandy

uscav8r

True, but it also seems like one is forced into the higher speed ratings with the smaller profile, and that would contribute to stiffer sidewalls also.

Any rubbing? Does it look like you may be able to fit a 255/40-18 or a 245/45-18 with the wheel turned in? These size more closely match the 215/55-17 diameter that is on my GLE now.

When are you gonna put up some pics?

ABS

Well, I've been driving the car since Friday night and I can tell you that I am getting absolutely zero rubbing! The wheels look nicely tucked, and since they are a silver color similar to OEM, I don't think they stand out dramatically while I'm driving which I view as a good thing since I think cops target cars that "look" decked out.

Limsandy: Thanks for all your help with this . . .

In regard to optional tire sizes, I don't think a 255 is in spec for an 8" rim and if you went to an 8.5" rim, I think you would want a lower offset, perhaps 35 would be good. I'm fairly certain a 245/45 would fit just as well as a 245/40 except it would be taller. This could be good for absorbing bumps and decreasing the risk of damaging a rim. However, please note, that I had been running 225/55/17 snow tires on my OEM rims. One thing I noticed was a big drop in performance. I think the combination of the heavier tire and the taller wheel resulted in the decrease in performance. I am much more satisfied with the acceleration now that I have the lighter rim/tire combination on the car. So far with the 245/40/18, I haven't hit any aweful potholes where I was worried about rim damage. On the other hand, I am running a lot of pressure to try and avoid that issue. Depending on how much you trust my air gauge, I'm running between 40 and 45 psi.

Some things I have noticed are the following: I am getting more torque steer than before, the tires track nicely in the straights and have a fairly responsive turn-in. I'm finding it much easier to weave through traffic now than before. As stated above, acceleration is improved. I haven't yet noticed an improvement in fuel efficiency. I am noticing now more than ever that the rear KONI's are dramatically outperforming the GR2 struts I have on the front. I'll probably need to replace the GR2 sometime soon.

Oh, one last thing, I was asked about the 215/55 tire size. I'm not positive, but I'd be surprised if Nissan changed the speedo depending on the tire size - it's just too expensive. The 215/55 is not too far off from the wheel height of the 225/50. Having said that, I think you'd be safe with either a 245/40 or a 245/45 on an 18" rim. If you want a decent summer tire which is also light, you might consider the Kumho Ecsta MX . . . I almost bought that one instead of the Falken.

uscav8r

Sounds like everything worked out! I am curious as to what the measurements you took before are with the new setup, in addition to any clearance space on the inside corner when turned lock-to-lock...

ABS

Unfortunately, with the tire mounted, it would be very difficult for me to take new measurements. What I can tell you is that there are no fitment/clearance issues. Also, I haven't experienced any rubbing on the inside edge of the tire against any body parts even with the wheels turned lock to lock.