18's on a 370z

Gregor12

I have heard different stories about diameter making a difference. It depends on the type of car as well. Here's a good read I found on it.

***If the tires up front differ in diameter from the ones in the rear, other kinds of handling defects can occur. If your car is front or rear wheel drive only, and you have compensated the difference in ride height, the only difference will be a difference in grip. A larger diameter tire will have a slightly bigger contact patch than a smaller one, and hence it will provide just a little more grip.

If your car is full-time 4WD, tire diameters can influence the amount of steering your car has very dramatically. Suppose the front tires are larger than the ones in the rear. The front end of the car will tend to travel a greater distance than the rear. Around a corner, the paths covering the largest distance are located towards the outside, and the short ones are located on the inside. So, the front end will want to go around the outside, and the rear will want to go right on the inside, making the car point outwards. In other words, the car will understeer horribly. It will feel like a ‘sticky’ kind of understeer too, slowing down won’t help very much, and braking will only help for a very short time because the car will very quickly try to return to its understeering state. The opposite can also happen: bigger tires in the rear will make the car oversteer very badly. ***

As stretched as that 285 is in the picture I would recommend going with a 305/30. Technically, if the tire brand and model remain the same, a 305 size tire should give you about half an inch on each side of the wheel. A 305/30 is just a tad bit shorter in the diameter so that will remain the same as well.

Again, all this is assuming that the calculator posted above is accurate.


Sent from my iPhone using Tapatalk