18's on a 370z

carlitos_370z

Great bro! Thanks a lot for the info... but im a bit confuse lol. I have to go with the 295/35 or 295/30?


Btw yes my front tires are 285/35. Im following instroctuions lol I wabt to rub square setup but I dont expect that the rear tires on the 18x11 wheels are going to look so stretch

I just want to intall a wider tire in the rear to fill that wheel lip without having problems with the traction control..

Thanks

Gregor12

I see what you're going for now haha. Can you post a pic of the rear? Maybe you have room for a 305/30.


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Gregor12

This calculator might help you decide as well. I know it may not be 100 percent accurate as all tires tend to vary when it comes to size depending on the brand. Post a pic of the rear to get an idea of how stretched the tire is now with the current size you're running and that will help a lot. Here's a link to the calculator as well.
https://tiresize.com/calculator/

If your offset would work in the rear with a 315, this would be the perfect setup in my opinion. Rear would look amazing.



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TN.Z

26.7" diameter is stock so whichever is closest to that.

Check the specs on the actual tire you plan to buy, sometimes the same size tire from different brands can be very different actual measurements.

Gregor12

True. But he needs to match his front diameter and the stock diameter. Each corner must be within a certain range to not trigger traction control


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TN.Z

Yeah I missed that front size in his post. I think I read somewhere they need to be within 1" to not set off the TCS. So your recommendations above would be the best bet

Gregor12

I think I read that as well but cannot confirm the truth haha. It seems reasonable though...


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carlitos_370z

Here is the pic guys! Thanks a lot for the help

https://flic.kr/p/QxEQAq

I think im going with thw 295/35 cause I know is hard to find more than that here on PR

Jonny

I'm not to disagree with anyone, but the front oem tire size is taller than the rear. Nissan did this so the car can understeer, which is a lot safer than oversteering. The 350z had slightly shorter tires in the front than the rear and they constantly spin out.

The traction control system in our cars is not very sophisticated, so going with different tire size should not be a problem. In the summer I'm going to run 275/35R18 in the front with 295/35R18 in the rear.

carlitos_370z

Thanks Jonny! I think im going to call this Monday to order the 295/35/18 tires

abm89

Not sure if the understeer is from how tall the tire is, rather than its width. The narrower front tire will definitely contribute more to the understeer. You're right about the TCS. It's useless.

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Jonny

^ Apparently it does affect it. There is a guy that comes into my work who is an enginner for continental tires and gave me a lesson. Honestly I don't think it will have an enormous effect bit it does affect it a little. Also the cost of the tire is also a factor.

TN.Z

Does it have something to do with the power rotation speed having more grip? I jut can't see how else tire diameter would matter much...

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.


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Gregor12

This is a 305/30/18 on a 18x11.5. I definitely think you should go this route.



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