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Discussion Starter #1
I know what the numbers stand for...example: 265 - width of tire/35 - sidewall height/19 - wheel size...

How does each change affect handling though? A wider tire would make you handle worse or better? A taller sidewall would affect what? Understand what I am asking?

--Brandon (trying to understand suspension and braking a little more)
 

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Discussion Starter #2
Got some answers on another board...

Originally posted by yugo on 350zmotoring.com
the wider the tire the better handling you`ll get.. bigger sidewall will give you a smoother ride and protects the rim better....
If you are going for performance consider 18in wheel and if you are looking for a little more bling go with the 19in wheel..


My reply:
Well, i'm going with 19" just because personally I can tell a difference between 18 and 19's but really can't between 19 and 20.

Thanks for the info. Will width affect oversteer or understeer too? Usually with every performance upgrade there is at least one negative about it (not price or look either).

How tall of a tire would you go with on 19's? 35?
Originally posted by yugo on 350zmotoring.com
To take care of over/understeer add some sway bars and that should take care of that.. And dont worry about negative effect of wider tire because as you do more and more MODS you will need wider tires in order to stick to the road.

And yes .. go with the 35 all around....


My reply:
Cool, thanks. What's the widest tire you can fit without it sticking too much out of the side in the rear?
 

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If you want to reduce the standard understeer which is a trait of the zed, (1) fit stiffer sway bar to the rear (2) fit same size tyres to all four corners.

Going with a wider tyre will not necessarily give you better grip, that all depends on the rubber used in the make up of the tyre. Bear in mind, the wider and larger rim size will give you a harsher ride due to the reduced sidewall.

IMO changing swaybars gives the best result for handling in the zed. The adjustability gives you the option to set up the car how you like to drive. Then you can decide whether you need to start playing around with the tyres. OR, if you want to start with the rubber first, then get rid of the standard staggered wheel set up.

Cheers
 

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Discussion Starter #4
Forgot to add to this thread what the final answers were.

Originally posted by 510dat
Ok, only dealing with tires...

You want different tire sizes based on what you are trying to accomplish. If you look at a 'funny-car' drag racer, they have giant tires in the back, and bicycle tires on the front. Since they don't really have to turn, lighter fronts are better. But, since you and I want to be able to make that U-turn, you need bigger tires on the front (well, wider than those bike tires).

It's all about ratios. The wider the fronts are compared to the rears, the easier it is to turn. But... you don't want it to get twitchy, because curbs are not your friend.

The wider your rears, the more likely you are to go in a straight line, and the more acceleration traction you have, but the harder it is to turn.

If you have lots of power, you need big rears to get it to the ground. Small tires will spin (more) easily. If they spin while you are taking a fast turn, your rear completely loses traction and your car spins around, too.

So, wider = more grip on that end (except in rain, when wider may/can = hydroplane, ie surfboard).

Stock, the 350Z is a bit wider at the rear (225 front, 245 rear). This will mean better traction in the rear, so you will have good straight line traction, but tend to 'plow' in a turn. Not badly, just a bit. This is generally safer than the opposite (old Porsche 911's can get real twitchy because of all the weight in the back. Notice the newer models have very wide rears?); most production cars have this tendency built in.

Lots of people like putting bigger tires and/or wheels on their car. Wheels bigger than 17in are mostly for show, and they get much more expensive. The advantage to bigger wheels is a bigger contact patch front to back (think wagon wheels), and slower wheel speeds at faster car speeds.

The downside is, the bigger the wheel, the heavier it gets. And even worse, the farther away from the hub that weight is. Physics says, the farther from the hub your weight gets, the harder it is to spin it. So a 20 pound 14" wheel is going to be easier to spin than a 20 pound 17" wheel. And, the more energy you spend spinning your tires, the less energy you have to accelerate your car.

So what do you want? If you want to drag race, get big rears. If you want to autocross, probably getting the same size (245-ish) all around is better. If you just want to look good, get 20" chromed wheels. But if you get spinners we will have to hurt you.


Originally posted by 510dat
Second part (still just tires)...

The /35 is another ratio; 35 means "35% of 265, measured from the rim to the tread"

So, the bigger this second number, the taller the tire will look compared to the wheel.

Old style tires, ie 185/70 R14 from your old 1975 Buick, are really "tall."
Taller tires soak up more bumps from the road, and therefore give you a comfy ride. Mmmm, Buick, squishy tires, squishy springs, squishy shocks... it's just like a waterbed...

But, in a hard turn, the sidewall can flex, and that makes your handling sloppy. So, all other things equal, the shorter the sidewall, the less flex, the sharper/crisper/more precise your handling.

Up to a point.

Somewhere on here, knowlegeable people were saying that less than /50 doesn't really make much difference. Also, really short sidewalls + potholes = bent rims. The tire takes up a LOT of bumps, so the less tire you have, the more work your suspension has to do. Which is good and bad, because it's much easier to control what your suspension is doing than your tires.
 

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I can honestly say that upgrading your tire size does make some of a difference, as does tweaking your suspension. When I had my Z32, the stock tires were 225's, and I went to 245's all the way around. ****, what a difference. I took it to a track and took corners like crazy, and one other Z with stock tires couldn't hang. So yes, it does make a bit of a difference.

Personally, I feel staying with 18's gives me better choices for tire brands and cost. I also agree that keeping the tire sizes the same at all four corners is beneficial, but I guess Nissan thought differently. :dunno: I was looking at my tires yesterday and thought the next time I buy tires, it will be at least 245's for all 4, unless I get new wheels to go with it. I still like the staggered wheel look, but if I can't do it, then I might just get the same tire sizes.
 
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