Why 19?

jeffreyfranz · 02-28-2010, 07:26 PM

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.

theDreamer · 02-28-2010, 07:32 PM

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.

GTRFAN · 03-01-2010, 06:24 AM

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

jeffreyfranz · 03-01-2010, 11:04 AM

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.

fairladyZ34 · 03-01-2010, 11:19 AM

cosmetic?

NXTAZEE · 03-01-2010, 11:56 AM

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.

Ryan@Forged · 03-01-2010, 03:16 PM

Quote:

Originally Posted by jeffreyfranz

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.

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

jeffreyfranz · 03-02-2010, 12:25 AM

Thank you, Ryan, much appreciated.

import111 · 03-02-2010, 01:39 PM

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.

gatorfast · 03-02-2010, 01:59 PM

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).

Chupacabra · 03-02-2010, 02:11 PM

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.

theDreamer · 03-02-2010, 02:15 PM

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.

m4a1mustang · 03-02-2010, 02:20 PM

Quote:

Originally Posted by Chupacabra

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

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.

Chupacabra · 03-02-2010, 02:23 PM

Quote:

Originally Posted by theDreamer

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.

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

Sharif@Forged · 03-02-2010, 03:53 PM

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.

02-28-2010, 07:26 PM	#1 (permalink)
jeffreyfranz Base Member Join Date: Feb 2010 Location: San Luis Obispo, CA Posts: 139 Drives: '10 370Z PG M6 Rep Power: 15	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.

02-28-2010, 07:32 PM	#2 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4210	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. __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

03-01-2010, 06:24 AM	#3 (permalink)
GTRFAN Track Member Join Date: Dec 2008 Location: Melbourne Posts: 586 Drives: 370z Titanium 6MT Rep Power: 18	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 __________________ My Zed

03-01-2010, 11:19 AM	#5 (permalink)
fairladyZ34 A True Z Fanatic Join Date: Aug 2009 Location: Central NJ Posts: 1,577 Drives: 08 G37S Black M6 Rep Power: 19	cosmetic? __________________ From Z to G to BMW and back to a G! Nismo for life

03-01-2010, 11:56 AM	#6 (permalink)
NXTAZEE Track Member Join Date: May 2009 Location: Vancouver Island Posts: 530 Drives: 2010 370Z 7AT Rep Power: 17	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. __________________ 2010 Carbon Silver 370Z 7AT charcoal int. sports package \| Clear Bra \| Invidia Gemini CBE \| CF B-Pillars \| CF Fangs \| CF Z emblems \| Swift Springs \| 20mm & 25mm Spacers \| SPC Camber Arms \| Brushed Aluminum shift knob

03-01-2010, 11:04 AM	#4 (permalink)
jeffreyfranz Base Member Join Date: Feb 2010 Location: San Luis Obispo, CA Posts: 139 Drives: '10 370Z PG M6 Rep Power: 15	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.

03-02-2010, 12:25 AM	#8 (permalink)
jeffreyfranz Base Member Join Date: Feb 2010 Location: San Luis Obispo, CA Posts: 139 Drives: '10 370Z PG M6 Rep Power: 15	Thank you, Ryan, much appreciated.

03-02-2010, 01:39 PM	#9 (permalink)
import111 Track Member Join Date: Feb 2009 Location: Tucson, AZ. Posts: 622 Drives: 09 Nissan 370Z Rep Power: 191	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.

03-02-2010, 01:59 PM	#10 (permalink)
gatorfast Base Member Join Date: Jan 2009 Location: SoFla Posts: 120 Drives: Z4 M Coupe Rep Power: 289	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).

03-02-2010, 02:11 PM	#11 (permalink)
Chupacabra Enthusiast Member Join Date: Jan 2009 Location: Weston, Florida Posts: 477 Drives: 09 Nissan 370z s M6 Rep Power: 200	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. __________________ Where are my aluminum pedals?

03-02-2010, 02:15 PM	#12 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4210	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. __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

03-02-2010, 03:53 PM	#15 (permalink)
Sharif@Forged The370Z.com Sponsor Join Date: Dec 2008 Location: Marietta, GA Posts: 840 Drives: 2009 GT-R, 2010 370Z Rep Power: 18	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. __________________ Sharif@Forgedperformance.com General Manager/Certified Tuner/NASA-PCA-BMWCAA Instructor JRZ RS1's Available NOW...PM me Cobb ProTuner, Uprev ECU Flash, FCON Vpro, Haltech, Motec Certified