I guess I am confused at why you felt the need to restate something I already said? So outside of the manual have you found anyone that has had issues?

 

My apologies, it was I that didn't catch your earlier posts

As far as issues, No, I can't say that I have; but then I don't pay as much attention because I don't have an X. Even so, I can't say that I would be reassured much by the lack of there being many documented cases on the forums. Perhaps people who are foolish enough to run diameters severe enough to cause damage aren't the same people who frequent boards.

Anyway, since it involves potentially advising someone to disregard an already expressed caution at THEIR direct financial peril, a better, more prudent question might be: "Are you positive there have NEVER been any cases of damage resulting from operating with different diameter tires?"

.

 

I have the X and recently put on 19" rims, 19x8x30 front and 19x8.5x33 rear. Tires are 225/40/19 front and 245/45/19 rear. Sometimes the AWD starts to blink even if I am driving at 40mph. The overall tire diameter difference is 16mm or 0.6". I am thinking of changing the front to 225/45 (6mm diff), 235/40 (8mm diff) or 245/40 (0mm diff but stick out more on the side). Any other suggestions?

 

My guess is that those 245/45 rears are what's tying you up; not many good choices to mate them with. Take a look at the tire calculator link I posted above; you can see if you changed the rears to either a 245/40 or a 255/40, then a 225/50 in the front would yield about .1" difference in diameter. Alternatively, if you changed the rears to a 265/35, then you could put a 235/40 on the front and also have a .1" net difference.

Bear in mind, these number are all in "theoretical" diameters; it's just a first start. To really get the actual diameters, you'd need to look up the specs on the specific tire make and model you're considering (TireRack has specs on most) because there is variation in call-out size vs. what sits on the road. Also, I am not making any claim that these will fit your car with your wheel offsets, but I'm sure others here could give you that or you could search a bit. G/L

 

I'm running 19x9 +41 235/35/19 Fronts and 19x10 +37 275/30/19 Rear with no issues

 

Yep, as expected because those diameters are basically identical (even closer than the ones I offered above), but then a 30's profile is definitely getting into rubber band territory

 

Your right I drive real slow to avoid potholes. That is a definite drawback, but I only run the 19's for 6 months out of the year.

 

That's got to be a fun 6 months though

Looking at your sizes again, I did notice they're shorter than stock, so I think your speedo probably reads too fast (about 5%), but it must also help in the 'get-up-and-go' department a bit to make up for it.

 

I wanna run a staggered set up on my 04 g35x 18x8.5rim with 225/40/18 tires front.18x9.5 rim with 255/40/18 rear.Ive done the tire calculator and its gonna be .94 total difference in diameter but it didnt put the rim width difference into account.I think i will be fine just wanted to be sure.Any input?

 

I realize this is an old thread, but to answer your question the tire sizes you listed are 3.8% different in circumference. This would be a problem on RWD models and I imagine a bigger problem with your X. The rim width doesn't matter when making these calculations.

On RWD, the difference needs to be less than 3% to avoid VDC kicking in. For AWD, the tires need to be the same circumference.

If you ran a 225/45/18 in front and 255/40/18 in the rear, there would only be 0.2% difference. That might be close enough.