lemmiwinkz

this is going to be a noob question but i looked a little with the search and cant find anything. i am pretty set on AME's TM02's but i am not sure on the size. i either want the 18x9.5 f 18x10.5 r or the 19 inch of the same widths. i would like the pros and cons of both. ive heard that the 19s are a harsher ride but if i got 35mm sidewalls for either size then shouldnt that make the ride the same? (285x35 18 or the 285x35 19)

davidv

iTrader: (2)

Both 18 and 19 inch wheels will be fine. Pick whatever suits your needs.

hellsoldiers08

iTrader: (3)

they say 19 for looks 18 for all around and 17 for performance. I got 19's recently and thought the ride was smoother! and love the amount of traction i have now! i see have now get been able to break loose the car and im scared to even want to push it to the limit because idk what the limit is yet!.

diablox1

iTrader: (7)

wtf did you just say??

terrasmak

iTrader: (8)

35mm sidewall?

Using an aspect ratio of 35 on either a 18 or 19 will give you very similer ride, but you would actually need a 295/35-18 or 275/40-18 cause the 285 is actually to short for the car. When using the proper height tire, same model tire, 18's will have a slightly softer ride

sry110

iTrader: (17)

True.

Depending on the stiffness of the tire sidewall. A stiff sidewall 18" tire may feel the same as a soft sidewall 19" tire for a given width and outer diameter (and whatever the corresponding sidewall aspect ratios are).

lemmiwinkz

i thought ive seen some people running 285/35 18's and like 255/35 18's front on their z's? actually i know i have, so why would 285/35 18 be to short?

sry110

iTrader: (17)

As an example, the OEM tire size for a 2006 350z enthusiast model is 245/45/18. The theoretical outer diameter of this tire is 26.68". Meanwhile the theoretical outer diameter of a 285/35/18 tire is 25.85". Keep in mind that your tire is the last "gear" in the total gear reduction ratio between the flywheel and the pavement, and the car's odometer, speedometer and various types of telemetry (e.g. TCS and VDC) are programmed accordingly. It is ideal for your aftermarket tire choice to maintain as close as possible to the same outer diameter as the OEM tire size.


For what it's worth, to use a 35 series tire on an 18" wheel and maintain the OEM outer diameter, it would have to be a 315 width (i.e. 315/35/18).

By the way, the math I used was:

Tire O.D. = Wheel Diameter + [ (Tire Width) x (Aspect Ratio) x 2 x (1/25.4) ]
where wheel diameter is in inches, tire width is in millimeters, and 1/25.4 converts millimeters to inches.

sry110

iTrader: (17)

Another thought, and this may be a very minor point, but decreasing the overall tire outer diameter will cause artificially high odometer readings. Since the tire's circumference is smaller, it will need to rotate farther for a given unit of linear distance (i.e. more wheel rotations per mile). Since the sensor for the odometer is reading wheel revolutions to calculate miles driven, it will end up showing that you've driven more miles than you actually have. In this case the circumference of the aftermarket tire is about 3% smaller than the OEM size, so I would expect the mileage to read about the same 3% high. (Probably not a big deal because if you are selling a car with 100k or 103k miles on it, what difference does it really make?)

lemmiwinkz

ok that all makes sense. and i knew that the vdc will act funny if you through some weird tire sizes in there. but what i understood is that the computer reads the front and rear tires rotation and takes into account the percent difference between the 2.

for example, based off the overall diameters, the 245/45 r18 (26.68in overal diameter) is 2.73% larger than the 225/45 r18 (25.97in dia) <stock

nismo
the 265/35 r19 (26.3in dia) is 2.29% larger than the 245/45 r18 (25.71in dia)

380rs
275/35 r19 (26.57in dia) is 3.34% larger than the 245/45 r18 (25.71in dia)

recommended tire size for LMGT4
275/40 r18 (26.66in dia) is 3.69% larger than the 245/40 r18 (25.71in dia)

the size i want
285/35 r18 (25.85in dia) is 3.31% larger than the 255/35 r18 (25.02in dia)

so that puts the 285/35 r18 and 255/35 r18 right in the middle of these stock tire sizes. #1 nismo (2.29%) #2 stock (2.73%) #3 mine (3.31%) #4 380rs (3.34%) $5 LMGT4 (3.69%)

lemmiwinkz

oh and as far as the miles thing goes im not to worried. im going to keep mine forever (i want to be like one of those old guys that drives around a nice, clean looking 240z)

and as for the final gear, dosnt making the tires a tad bit smaller make the final gear a little smaller as well, allowing for faster accelerations? (not even noticeable, but theoretically an increase)