Which Wheel? Offset question

[bullittandy]

Can someone help me understand offset? Stock 1997 Q45 16X7 wheels have an offset of 40mm. I'm looking at a set of 18X8 350Z wheels that have an offset of 30mm. 1. Will these bolt right on? Rubbing? 2. Will the wheel face be pushed out or tucked into the fender as compared the stock wheels? 3. Also I know ride quality will be degraded but how much? (This part of the question is for people who have actually driven or ridden in a car that has a 2" increase in wheel diameter.

Thanks!

[maxnix]

Can someone help me understand offset? Stock 1997 Q45 16X7 wheels have an offset of 40mm. I'm looking at a set of 18X8 350Z wheels that have an offset of 30mm. 1. Will these bolt right on? Rubbing? 2. Will the wheel face be pushed out or tucked into the fender as compared the stock wheels? 3. Also I know ride quality will be degraded but how much? (This part of the question is for people who have actually driven or ridden in a car that has a 2" increase in wheel diameter.

Thanks!

1.) What tire? The wheels themselves won't rub.

2.) Out by almost an inch.

3.) Back to the tire again. PS2 are amazingly smooth and compliant. But 8" is a pinch on 255/40-18.

[elwesso]

I think id prefer a 245-45 on an 8in... I have 245-40s on my 8in wheels and they fit nice... 255s might be OK, but maybe a litlte wide for my tastes... 255s fit great on 8.5in wheels.

The 350Z wheels will fit GREAT on the Q .....

[Falkdesigns]

... 255s might be OK, but maybe a litlte wide for my tastes........

WHOA!!! I just had to do a double take!! You feeling alright Wes?? Glad to see your tire-to-wheel-width tastes have changed a bit! Good stuff man.

[Rex]

Offset cannot be (directly) compared if the wheels are of different widths, that in itself is generally confusing. Using a little math (or a nifty online tool) can help you understand the "clearance" differences between wheels.

[qsiguy]

That's a neat and usefull tool Rex. Takes care of all the guesswork and estimating.

[szh]

Offset cannot be (directly) compared if the wheels are of different widths, that in itself is generally confusing. Using a little math (or a nifty online tool) can help you understand the "clearance" differences between wheels.

Treat this tool as only a starting point! Remember that tires of the same size tend to have different section widths and cross-section shape, etc. Particularly an issue with low aspect ratio tires.

Ultimately, in the extreme size conditions (wheel or tire), one brand/model of tire might work where another of the same size might not - even from the same mftr.

Nothing beats actual fitment tests. Then, getting the help of prior knowledge and experience, or from experts (www.tirerack.com) makes the most sense!

Z

[deepsouthq]

Just put a set of 18 x 7.5 (35 offset) Murano 5 spokes on my 97 Q yesterday. I am thrilled with the look and ride. I went with BFG g-force KDWS in 235/50/18 from tire rack. I have a tire store so they cost me less, but they are on the website at $75 each. 400 treadwear, 150 mph speed rating, 97( i think) load rating and less than 7 ounces to balance all four.Overall height is .7 in. taller than stock, but they push out and fill the wheelwells beautifully. jim

[maxnix]

There is this one http://gs.tolan-hoechst.com/tirecalc.htm (tells me my 255 tires are too narrow!).

I really like this one: http://www.bigcustomwheels.com/info_specs.jsp

It along with Blake Bauer at Tire Rack personally reviewing their AutoCAD files helped me to achieve a fitting that wasn't in the books.

Most people do this backwards, deciding on the wheels first, then finding a tire to fit it, or even force a tire to fit.

It is much better to decide on a tire that will work best first, then find a wheel that will work with the tire, hubs, brakes and calipers, and then the car.

Many owners spend entirely too much time on what the static looks of the car will be with a certain wheel (almost ignoring the tire except as wheel dressing) rather than the dynamic performance improvements they should be attempting to achieve.

Of course, if your suspension is not to OEM as new specs, you are throwing money away regardless.

And the tire is the only part of the car interacting directly with the road surface. Skimp here and all else is for naught or just the buds at the drive-in.

Wes is correct that a 245/45-18 will be the best fitment on your current wheels. But get the right one that is 100 load rated.

[szh]

There is this one http://gs.tolan-hoechst.com/tirecalc.htm (tells me my 255 tires are too narrow!).

This is better for sure! But even here, there is a bit too much simplification! If you look at my tire spreadsheet, you will see that tires can have different rolling revs per mile for the exact same size tire. Even from the same manufacturer!

Means that it is best to look at the specific tire information (like from Tire Rack or my spreadsheet) to get the best accuracy.

Many owners spend entirely too much time on what the static looks of the car will be with a certain wheel (almost ignoring the tire except as wheel dressing) rather than the dynamic performance improvements they should be attempting to achieve.

Very, very true, unfortunately!!!! Looks are way secondary to performance, IMHO.

Wes is correct that a 245/45-18 will be the best fitment on your current wheels. But get the right one that is 100 load rated.

Yup!

Like the Goodyear Eagle F1 GS-D3 245/45-18 100W. Tire Rack has a pretty darn good price going for them right now, including a $100 "card" (don't know what that means yet) and a "Cars" soundtrack CD (cool!). I am about to order four tires from them since my M45 is now down to 4/32" tread depth (3/32" in some sections of the tread).

By the way, I believe in changing tires before you get to 2/32" (or less! ) - particularly if you live in rainy country!

Z

[szh]

I really like this one: http://www.bigcustomwheels.com/info_specs.jsp

Pretty good, but it is good of them to mention this caveat (ignoring the small typo): Quote »Assuming that this is OEM wheel/tire and there is no any problems with clearance on both sides[/quote]

Z