Why 19?
 

I have asked this question on forums for about two years now, and I still don't think I understand: What is the advantage of a larger diameter wheel and tire? The operator of one well-known internet tire website said that if all other factors were the same (i.e. width, profile), and thus the contact patch was the same, an 18" would have no advantage over a 17," for example. Yet, manufacturers appear to be going to ever larger diameters (19," 20"--what's next?).

Why do I care? Go to Tire Rack and see how many options 370Zs with the Sport Package have for tires. Hint: It is a very small number.

Can someone please explain this once and for all?

Thank you. :tiphat:

Do not 100% trust tire rack on the tires they spit out, you can adjust it slightly on size and such. Just do some searching (here & Google) for a tire calculator and you will see what changes in size/width/etc.
Well, 18" v. 19" usually comes down to weight & rotational mass, but that is basically if you plan to track the car. Even then, a 19" might be the better route because of a BBK fitment issue with smaller wheels.

The lower the side wall profile, the better the handling...generally. This would not be true for 22" wheels with a really thin tyre profile but it is true for most wheel diameters.

The thing to remember is that, the overall rolling diameter (circumference) MUST stay the same when you upgrade. So if you go from a 17" to 20" rim the tire profile % must get a lot smaller to maintain the overall diameter.

Tire sizes are also a strange beast with a mix of metric and imperial measurements.
285/35/20 means - 285 mm width/35% of 285mm sidewall/20 inch rim

Thank you, Dreamer and GTRFAN. Your responses were helpful. I'm still not sure anyone has explained why, say, 19" is more advantageous vs. 18", but I'm learning as I go.

cosmetic?

I think one advantage would be handling, because a lower side wall will not roll and move as much when cornering. Another advantage would be weight. And of course aesthetics, larger rims just look better than small rims. The last one is subjective of course but most would agree.

There are many factors to think about. In most cases a 18" would actually be more advantageous over a 19" due to the fact that it will likely have less rotational mass. However, with this in mind you will also have a much harder time clearing big brake kits. Also, the 19s seem to be more cosmetically pleasing to the eye, although that is merely personal opinion. There are also several 19s which come in an 11" width, where it is harder to find 18s made in an 11" width. Just a few things to think about :)

The 370Z does 0-60 in low 5's and the 1/4 in low 13's and pulls .93-.99 g's on a skid pad. 19's seem to work just fine for it. Also Ferrari, Lambo, and other supers and exotics use 19's too.

I think the main reasons that a typical car the like the 370z would come with bigger wheels would be for looks (fills out the fender better) and percieved value (people think that because a wheel is bigger it therefore must be more expenseive and desireable).

http://upload.wikimedia.org/wikipedi...a_One_Tire.jpg

380/44/R13 and those things hold up to over 4 lateral g's....



I think its mainly due to rotational mass, but since the difference between 18 and 19 is not that great, cosmetics then come into play, with the 19's filling out the wheel wells more.

Actually, it does not fill out the wheel wells anymore or less.
When you increase the wheel size (18->19) you must change the tire size to adjust rotational measurements & speed.

Keep in mind that those are sizes that the rulebook regulates, so they aren't always necessarily ideal. Example... NASCAR mandates a 15" wheel, but if you let the teams choose they would probably run a 17-18" wheel to fit bigger brakes.

As with NASCAR/F1... those sidewalls are incredibly stiff.

Yes you are right there... so lets say it Optically seems fuller.

From a performance standpoint, the highest performance wheel is one that is large enough to just barely clear the brake caliper and rotor and no larger. Hence, the tiny wheels used in F1.

As Ryan and other mentioned, maybe people select wheels from an asthetic standpoint so there are many other factors to consider.

OEM's are simply following the bigger is better thing that consumers demand. Back in the 80's a 15 inch wheel was considered cutting edge and massive. Now a 19 is the new standard, and many cars come with 20's from the factory.

so i should feel good that there isn't even a pinky tip width between my brake caliper and my 19" oem wheels?

It's the space between the barrel and the caliper that is most critical from a performance standpoint. :)

I don't know. It all depends on your purpose. If you're building a car for Redline Time Attack and you're in the Enthusiast or Street class, the widest tire you can use is 285, so there's no point in getting a 11" width wheel. Therefore, a 10" width or maybe even 10.5" width wheel would be better in this situation. A lot of 18" wheels clear the Akebonos and even the AP Racing BBK. Go check out the Robispec 370z if you want an excellent example of a purpose-built machine. On a side note, my track wheels are 18x10 all around haha. I didn't really find the need for 19's. :tup:

why 19? bc theyre young, innocent, nieve, and can be talked into all kinds of your wife/gf won't do. wait whats this thread about?

And possibly saved yourself a fair amount of unsprung weight in the process, which was my original point. Thanks, OMGWTFBBQ (great name, BTW).

lol

So let me get this straight...

Will an 18" wheel fit on our sport package brakes?? I'm about to drop a hefty amount on some different wheels (Volks) and I would obviously like to save both $$ and unsprung weight if possible and go with an 18" if I can. (I track my car)

Enkei RPF1's and Enkei NT03+M's fit with no problem.

Another benefit of 18's over 19's is increased tire selection and cheaper prices. :tup:

Oh yeah. So do Enkei PF01's and SSR Type-F.

The reason a 19" wheel looks better than an 18 is that the wheel fills more of the wheel well, not the black tyre.

dunlop starspec's only comes in 18's. and they are the best tires according to car and driver

Cosmetics... 19's look nicer, for the z, they're actually wider so will provide a bit more grip.

on the track the 19's have a different slip angle, you need to be a better driver with the 19's...

18's benefits are: less likely to be stolen, better ride comfort (more side wall), cheaper to replace, less noisy, slightly more protection against gutter scrape and they're lighter.

Do you mean the Enkei PF-01 18" with the +38 offset--is that the one that fits over the Sport Package brakes? It's a nice looking wheel and may be a good deal lighter.

personal preference
 

I myself enjoy the look of 19's on the 370z. There is nothing wrong with 18's though. What I don't like is too big of wheels on cars, trucks, and SUV's. I just think that they need to be correctly proportioned to the vehicle.

On an extra note: The wheels and tires of the F1 car are a beautiful thing!

my point exactly, plus weight and cost :eek:

rep added for agreeing with me!

They are absolutely not... they ranked the highest in their lame *** compro... remember the PS2s were the benchmark...

And those tires do come in 19s