245/40/18 on a Y33?

[NY94J30]

Anybody running these on an 18x8 +40? No rubbing issues? Would a 235/40 be better? If they're okay, how flush are they?

[Rex]

GIven my limited knowlegde of Y33 width and offsets I'm thinking those would be sunken, but not sure if they'd rub on the inside or not.

[maxnix]

Too short. IT's better to have at least an 8.5" wheel width and run 245/45-18 (slightly tall) or 255/40-18 (perfect).

I run 255/40-18 PS2 on 18x9 +35mm on my wife's FGY33.

[NY94J30]

Brian, it's shorter in the same order of magnitude as a 255/40 is taller (i.e. OEM overall diameter = 25.85; 245 = 25.71; and 255 = 26.03.

I already have an 18x8 with a +40. So the question is, what's the right tire size; accommodating the need for a higher load rating ought not be a problem in any of these sizes. A 225/45/18 is actually the closest to OEM diameter at 25.92. I, however, wanted a wider tire.

[NY94J30]

Rex, as far as I can tell, OEM for the T model is a 17x7 with a +40. So an 18x8 would be a half inch nearer the fenders, if I'm not mistaken.

[maxnix]

You are correct, but it is really overall diameter and load capacity that separates the wheat from the chaff in the same tire model. The 255/40-18 is spot on.

I have driven short tires on two of my cars and the correct diameter with extra load capacity on all 3 later. The latter is preferable and noticeable.

Best explained by Q45tech's posts on reduced slip angels in the front.

I would be concerned that the +40mm with an 18x8 may interfere with the strut body. The 18x9 +35mm is very close, but does clear.

Stock 16x7 are +40mm. 17x7.5 are +30mm.

[NY94J30]

Thanks, Brian, good info. I'll check Dennis' post. And I suppose a test fit is in order.

[Rex]

I would be concerned that the +40mm with an 18x8 may interfere with the strut body. The 18x9 +35mm is very close, but does clear.

If an 18x9 +35 clears, an 18x8 +40 will actually have a little more clearance on the inside.

In short, I'm pretty sure you can get away with running them, just expect them to sit a little farther into the wheel well than you probably want.

[maxnix]

If an 18x9 +35 clears, an 18x8 +40 will actually have a little more clearance on the inside.

In short, I'm pretty sure you can get away with running them, just expect them to sit a little farther into the wheel well than you probably want.

Maybe yes, maybe no. +40mm is 5mm closer to the strut than +35. Wheel rim should be 12.8mm less 5mm = 7.8mm closer on the 9 as opposed to the 8, same diameter.

The 18x9 only has about 3mm or so of clearance from the strut.

The Nismo 18x8.5 +30mm would be good all around. From the Z33 track model rear?

Lastly, not all wheel offsets measure as they are declared. Best to fit to confirm.

[Falkdesigns]

My fronts are 19x9 +18 with 245/35's. +35 or +40 is extremely sunken, like the stock wheels were on Y33's.

[NY94J30]

If my math is right, an 18x8 +40 will be .1 inches (.25 in - 10 mm) more inset from the fender and .64 inches (.25 in +10 mm) nearer the strut than a 17x7.5 +30.

I'll have to do a fitting and see. But it may be time to rethink this. I know the general consensus on spacers.

These are what I was hoping to put on:

[Rex]

My fronts are 19x9 +18 with 245/35's. +35 or +40 is extremely sunken, like the stock wheels were on Y33's.

And there's some real world application that reflects what I was "figuring".

[maxnix]

If my math is right, an 18x8 +40 will be .1 inches (.25 in - 10 mm) more inset from the fender and .64 inches (.25 in +10 mm) nearer the strut than a 17x7.5 +30.

~25.4mm = 1 inch.

Fit first for sure.

I know Duy had fender interference issues with his 18x9 +25mm with 255/40-18 and Tein springs. More than I would tolerate on a street car.

[audiovisiony33]

I'm running 245/45-18 in the front and 275/40-18 in the rears on my 97 Q.I got the tire size based on the original tire diameter.

Check out the link and play around with different sizes.But make sure you don't go smaller size than the factory specs. and make sure rear tire diameter is no less than the front if going with stagger fittment. Or it will trigger tracktion (TCS/Slip) on the freeway speed.

http://www.miata.net/garage/tirecalc.html

[NY94J30]

I will do a test fit, hopefully, tomorrow. I'll take some pictures then, too.

I don't intend to stagger the wheels. If I decide to change the wheels, I will go with the FX wheels I already have.

[rhrabal]

Hi,I just put on (this past weekend, Feb 17th) new wheels and tires on my car. After reading and talking with the Forum, the decision was made to put 245-45 on my new 18-8 wheels. Unfortunately, the 245-45 were too wide to fit in the front and the tires rubbed against the shock towers. I had to go with a 245-40 and these seem to work fine. My only issue is these tires are slightly smaller in total diameter then the original 225-50 that we on the car. The 245-45 are roughly .80 larger in diameter then my original setup... the 245-40 are roughly .14 smaller then the original setup. Based on the tire/wheel calculator... 235-45 are roughly .47 larger then the original setup but I'm not sure these will fit since Discount Tire didn't have any in stock to test on my car. I was thinking of putting up some pics of my new wheel/tire setup and see what the Forum thinks. Hope this helps and good luck.

[maxnix]

You are peobably fine.

But you never said which brand and model of tire you mounted.

Beware of the dreaded Yoko 420 from Discount.

[Q45tech]

The FINAL rolling circumference is a function of inflation and weight on the tire.

Obviously equal rear tires are slightly larger due to lower weight with equal inflation................then comes the growth factor at high speeds.

[szh]

The FINAL rolling circumference is a function of inflation and weight on the tire.

Yup! Which is why I use the mftr's stated rolling revs/mile (if available) to figure out the effective speedo errors, for example.

Z

[StarPD]

Hi,I just put on (this past weekend, Feb 17th) new wheels and tires on my car. After reading and talking with the Forum, the decision was made to put 245-45 on my new 18-8 wheels. Unfortunately, the 245-45 were too wide to fit in the front and the tires rubbed against the shock towers. I had to go with a 245-40 and these seem to work fine. My only issue is these tires are slightly smaller in total diameter then the original 225-50 that we on the car. The 245-45 are roughly .80 larger in diameter then my original setup... the 245-40 are roughly .14 smaller then the original setup. Based on the tire/wheel calculator... 235-45 are roughly .47 larger then the original setup but I'm not sure these will fit since Discount Tire didn't have any in stock to test on my car. I was thinking of putting up some pics of my new wheel/tire setup and see what the Forum thinks. Hope this helps and good luck.

Interesting. I have on order from Discount Tire 18x8-40 TSW "Kyalami" wheels, which have arrived and look pretty good. Tires coming in are 245/45ZR18 100W Bridgestone RE050A "Pole Positions". These are going on a 2005 Q45 (F50). The tires are due in tomorrow. I'll have them installed and check for clearances, then get a 4 wheel alignment at Midway Infiniti.

I'll report on fit then in a new thread, and as soon as I have a few miles, tell how they ride, steer, and handle.

[szh]

I just put on (this past weekend, Feb 17th) new wheels and tires on my car. After reading and talking with the Forum, the decision was made to put 245-45 on my new 18-8 wheels. Unfortunately, the 245-45 were too wide to fit in the front and the tires rubbed against the shock towers.

What is the offset of the wheel? You should have been fine with an 18x8 wheel and 245/45-18 tires. If the offset was 45mm or something high like that, then, yeah, you may have had contact!

With that width, I'd make sure to get about 35mm offset wheels to get a good fit.

Z

[szh]

Interesting. I have on order from Discount Tire 18x8-40 TSW "Kyalami" wheels, which have arrived and look pretty good. Tires coming in are 245/45ZR18 100W Bridgestone RE050A "Pole Positions". These are going on a 2005 Q45 (F50). The tires are due in tomorrow. I'll have them installed and check for clearances, then get a 4 wheel alignment at Midway Infiniti.

I think a 35mm offset might have been better, but you may get lucky with the 40mm.

I'll report on fit then in a new thread, and as soon as I have a few miles, tell how they ride, steer, and handle.

That would be good! I am interested in information about that tire too.