Question for any tire tech guy
 

Ok gonna change tires i'm new at this and have a couple of questions
Right now i have the 19in rays 245/40r on front and 275/35r on the rear.
question= i am gonna keep the 19in rays so when i change tires i would like just a little bit wider tire for both the front and back without changing anything about the car spacers lowering anything like that.so what tire size will fit without any adjustments to the car.

last question i know it came with asymmetrical tires fine
since you can't rotate anyway can one change to a true directional tire?

sorry to ramble hope that makes sense.

i suppose you can try 255/35/19 and 285/30/19.

yes, directional tires will work fine.

I now have 275/35's on the front and 305/30's on the back of my sport Rays. Looks great! You can go quite a bit wider with no problems at all. I have not lowered my car but I am running spacers.

AZ

If you are gonna lower the car, change up the specs a little and go with a smaller height. I would lower the height, if say you are going to go wider. Directional tires will be fine, especially for a car that isnt driven in snow or anything for the most part.

It all depends on how aggresive a setup you want. AZroadsters' setup is probably the most I would go on the Ray's.

Directional setup is fine. The non-sport wheels come with direction Yoko Advan's.

This is very helpful for comparing tire sizes:
Tire Size Calculator - tire & wheel plus sizing

The 305/30's are a little off - would 315/30 be too wide to fit the Sport wheel?

What do you mean by a little off? If you are talking about circumference, my Z with the set up I described reads about one mph off (low) on the speedo when comparing it to my GPS, which I am very confident is almost right on the money. I personally think that a 315 would be too wide for the stock 10" wheel. I think at the 305 looks good, but I always thought that the 275 on the 10" looked too small, meaning that the sidwalls angled in too much. The 305 is just about perfect.

Here's a picture of the rear stock wheel with a 305/30 Hankook tire.

http://www.the370z.com/members/azroa...rear-wheel.jpg

Too much. It will look too streched out.

Yeah, I meant the 1MPH off versus the 0.2 of a 315/30, but it isn't made anyway.

use a tire calculator.. u can probably get away with 255/40, 285/35 on 19s. 255/35, 285/30 will throw your speedo off quite abit..