Let's start the discussion on Z/28's aftermarket summer/winter wheel size

[Lightsaber]

Let's start the discussion on Z/28's aftermarket summer/winter wheel size



I'm not sure what jokes are the best to tell before we talk about size, so let's just get straight down to business.

A. Understanding the OEM size

6th generation Camaro Z/28's stock size:

Wheels:
Front - 19x11 5x120 +11mm
Rear - 19x11.5 5x120 +26mm

Tyres:
Front - 305/30ZR19
Rear - 305/30ZR19 (same as front)

These wide rubbers are obviously to help Z/28 corner, brake, and put down power better on a race track. Now, do you know why the Camaro Team chooses wheels of different width front and back? Here is a clue:



This slide is taken from the Z/28's Tech Background presentation (source: Z/28 Reviews). Mark Stielow, the programme's performance manager who presented that part, claimed that the "wheels are staggered [...] to improve rear tire handling at the limit." We know that when we use a narrower tyre for a wheel to have it installed in a stretched fashion, the sidewalls tend to feel as if they are stiffer. I guess that's what Stielow meant.

There are two slight problems associated with this (visually indistinguishable front and rear wheels with different width and offset):
1) A clueless owner/mechanic may put the front wheels on the rear, or the rear wheels on the front;
2) We can no longer equalize front and rear tyre wear by an easy tyre rotation.

For (1), an ad hoc solution can be simply marking the front and rear wheels with the word "front" and "rear." For (2), we will either have to change rear tyres more often than front ones, or take the hassle to dismount the tyres, cross-rotated them, mount them to correspondent wheels, and have them re-balanced.

Nevertheless, do ya wonder why didn't the Camaro Team simply use 19x11.5 +26mm wheels front and back, and put a pair of 15mm wheel spacers on the front? Wouldn't that also improve front tyre "handling at the limit?"

So there must be hidden or non-existent reasons that answer the following question:
a) Does narrowing the front wheels by 0.5 inches really save some significant weight?
b) If it has to be 19x11 on the front, why no 295/30ZR19 instead of 305/30ZR19 tyres?
c) Why use different offset front and rear wheels, instead of modifying front wheels hub or installing wheel spacers?

For now, I'd like just to assume that the Camaro Team was originally using ZL1 rear wheel and tyre combo (11" wheels and 305 tyres) front and back, then the test driver didn't like the rear sidewalls being soft, so they came up with some quick and dirty fix. That fix was to increase the rear wheel width by 0.5 inches. Hence this is where the nonsensical wheel sizes come from.

B. Coming up with aftermarket summer wheel size

Based on what we understand from the above discussion, I think we can simply order the following size for the summer:

Front - 19x11.5 5x120 +26mm; 15mm wheel spacers
Rear - 19x11.5 5x120 +26mm (same as front)

while retaining the OEM 305/30ZR19 size for the tyres. This is a good size still and all. You can find quite a range of choices to accommodate track, autocross, and street use. Example: Tire Search Result: Camaro Z/28

By having the same wheels, we can rotate the tyres easily and order a set of four tyres once a while, instead of ordering a set of two frequently.

C. Coming up with aftermarket winter wheel size

Aside from the less-enlightened drivers who drive to endanger during the snow days, driving a well-engineered rear wheel drive vehicle in the snow is plenty of fun! The rule of thumb for performance winter tyres is that 9" width for the wheels is about the limit. Tyre manufacturers usually don't make any winter tyres wider than that.

I think we can start like:

Front - 19x9 5x120 +26mm; 15mm wheel spacers
Rear - 19x9 5x120 +26mm (same as front)

These wheels go with 265/35R19 tyres, which make it possible for you to shop for winter tyres (example: Tire Search Result: Camaro Z/28, winter). At this size, you will have +0.4% diameter comparing to 305/30ZR19. You can also go for 275/35R19 size if winter tyres of such size is available and you like the beefy fashion. Regarding whether to go for 35 sidewalls and 30 sidewalls, here is a list of diameter change according to my calculation:

305/30ZR19: 0.00% (Stock)
265/35R19: +0.4% (35 sidewall is preferred for 265 width)
265/30R19: -3.4%
275/35R19: +1.5% (35 sidewall is preferred for 275 width)
275/30R19: -2.7%

Instead of 15mm wheel spacers on the front, you can also get 30mm spacers on the front and 15mm spacers on the rear if you don't like the "tucked-in" look of winter wheels. Nevertheless, be mindful to get (aluminium, no plastic!) hubcentric rings or spacers with the hubcentric collar that fits Camaro. I believe the factory hub size is 67mm. Example:

Front - 19x9 5x120 +26mm; 30mm wheel spacers
Rear - 19x9 5x120 +26mm; 15mm wheel spacers (same as front)

or:

Front - 19x9 5x120 +11mm; 15mm wheel spacers
Rear - 19x9 5x120 +11mm (same as front)

D. Your thoughts

Have you been thinking about getting aftermarket wheels? Rotating the tyres on your Z/28? Do the above discussion make any sense to you? Tell us your thoughts!

Cheers!

[Dr Chill]

Your solution of rear wheels all around using 15mm spacers will make the wheel stick out another 1/2" and may rub. The factory front wheel already sticks out too far for my tastes. Adding 1/2 inch isn't a consideration. I ordered 20x10.5 +15mm offset wheels all around. That will tuck the front about a half inch and leave the rears flush. You can do the same with a 19" wheel. I think the car will be a far better daily driver with a narrower tire up front. Alternately, using stock front wheels on all 4 will result in the rear tire sticking out too far. I already mounted my front wheel in back to see and that was my impression.

Also, adding 5mm or larger spacers would require you to add longer wheel studs in front. 30mm spacers are really not a great idea IMO.

[cliffy]

Just go to your SELLING dealer, give them your VIN, and get their best price, and they will have to add in the core fee of $50. Takes 2 weeks to get them

Mine were $617 plus 50 each plus sensors. Makes no sense to fool around with custom rims and pay $800 - 2000 each. I think the stockers are the best rims in the world for the car for the $$

19" Michelin Super Sports are very common in the size we need. They are OEM on some Mercedes and BMW and are about 340 each at Discount Tire. For me they are the best all around street tire for weather above freezing. I don't take my ride out in snow

[Lightsaber]

Originally Posted by Dr Chill

Your solution of rear wheels all around using 15mm spacers will make the wheel stick out another 1/2" and may rub. The factory front wheel already sticks out too far for my tastes. Adding 1/2 inch isn't a consideration. I ordered 20x10.5 +15mm offset wheels all around. That will tuck the front about a half inch and leave the rears flush. You can do the same with a 19" wheel. I think the car will be a far better daily driver with a narrower tire up front. Alternately, using stock front wheels on all 4 will result in the rear tire sticking out too far. I already mounted my front wheel in back to see and that was my impression.

The stock front tyres are indeed very wide for a RWD car. I think the Camaro Team was likely seeking better braking by doing that.

Originally Posted by cliffy

Just go to your SELLING dealer, give them your VIN, and get their best price, and they will have to add in the core fee of $50. Takes 2 weeks to get them

Mine were $617 plus 50 each plus sensors. Makes no sense to fool around with custom rims and pay $800 - 2000 each. I think the stockers are the best rims in the world for the car for the $$

Agreed. When money is an object, of course the OEM wheels are the best. They are also stronger than many lightweight aftermarket wheels with less load rating, which means we are less likely to crack the OEM wheels when hitting potholes.

Like how Dr Chill voiced that putting +11 offset front wheels front and rear can make rear wheels appear sticking out too much, so +26 offset rear wheels front and rear should be the way to go if one wants four identical wheels.

Originally Posted by cliffy

19" Michelin Super Sports are very common in the size we need. They are OEM on some Mercedes and BMW and are about 340 each at Discount Tire. For me they are the best all around street tire for weather above freezing. I don't take my ride out in snow

Michelin Pilot Super Sport is my favourite for summer street driving as well. It's the street tyre that feels the closest to slick tyres.

[blessedhellride]

Originally Posted by cliffy

Just go to your SELLING dealer, give them your VIN, and get their best price, and they will have to add in the core fee of $50. Takes 2 weeks to get them

Mine were $617 plus 50 each plus sensors. Makes no sense to fool around with custom rims and pay $800 - 2000 each. I think the stockers are the best rims in the world for the car for the $$

19" Michelin Super Sports are very common in the size we need. They are OEM on some Mercedes and BMW and are about 340 each at Discount Tire. For me they are the best all around street tire for weather above freezing. I don't take my ride out in snow

[Dr Chill]

While the oem z/28 wheel may be the best quality wheel for the price, there are better options for similar money or even less money in regards to street drivability. The wide front tires cause the car to follow every groove in the road and also stick out too far. They require the driver to concentrate 100% of the time just to maintain their lane on the highway or when negotiating curves.

All of the wheel experts I spoke with including John Purner of CCW recommended not using the Oem sizes for the street. On the track, they are king.

Using 26 offset 11.5" wheels in front with longer studs and big spacers is not advisable and will look horrible.

Ideally a staggered setup with 275-285 in front and 305-315 in back should significantly improve street manners. If rotating tires is important to you, a square setup with 10-10.5" wheels would work best as long as the offsets are chosen wisely.

[cliffy]

Originally Posted by Dr Chill

While the oem z/28 wheel may be the best quality wheel for the price, there are better options for similar money or even less money in regards to street drivability. The wide front tires cause the car to follow every groove in the road and also stick out too far. They require the driver to concentrate 100% of the time just to maintain their lane on the highway or when negotiating curves.

All of the wheel experts I spoke with including John Purner of CCW recommended not using the Oem sizes for the street. On the track, they are king.

Using 26 offset 11.5" wheels in front with longer studs and big spacers is not advisable and will look horrible.

Ideally a staggered setup with 275-285 in front and 305-315 in back should significantly improve street manners. If rotating tires is important to you, a square setup with 10-10.5" wheels would work best as long as the offsets are chosen wisely.

Part of the absolute joy of driving the car the way it is designed, is that it keeps you on your toes and hands on the wheel at 10 and 2. No time for texting or talking on the phone - its a pure drivers car. It goes where you steer it, brakes where you stop it. Road ruts from semis are a pain in the a-- but I don't stress. In default mode (in none of the track modes) I feel I am in good hands on the highways. Its made me much more conscious of all the f*%kups out there on the road

[Lightsaber]

Originally Posted by cliffy

Part of the absolute joy of driving the car the way it is designed, is that it keeps you on your toes and hands on the wheel at 10 and 2. No time for texting or talking on the phone - its a pure drivers car. It goes where you steer it, brakes where you stop it. Road ruts from semis are a pain in the a-- but I don't stress. In default mode (in none of the track modes) I feel I am in good hands on the highways. Its made me much more conscious of all the f*%kups out there on the road

I also enjoy driving with wide front tyres. Hell yeah, I can even apex within the lane on the highway. Some complain that cars with wide front tyres are annoying for road trips, but I find the opposite. I took two 10-hour road trip several months ago and the wide tyres (although these are on a different car) kept me awake and alert. It was overall a pleasant experience to drive a sportscar for all that 20 hours (as opposed to a car made for retirees like a Camry or a Lacrosse).

Yeah, right, you can sip latte, play with infotainment, make phone calls, text, sext, or watch a movie while driving with narrow front tyres, but I'm used to pulling over for a minute for this type of stuff. So I guess... wide tyres are not bothering me?

[cliffy]

Originally Posted by Lightsaber

I also enjoy driving with wide front tyres. Hell yeah, I can even apex within the lane on the highway. Some complain that cars with wide front tyres are annoying for road trips, but I find the opposite. I took two 10-hour road trip several months ago and the wide tyres (although these are on a different car) kept me awake and alert. It was overall a pleasant experience to drive a sportscar for all that 20 hours (as opposed to a car made for retirees like a Camry or a Lacrosse).

Yeah, right, you can sip latte, play with infotainment, make phone calls, text, sext, or watch a movie while driving with narrow front tyres, but I'm used to pulling over for a minute for this type of stuff. So I guess... wide tyres are not bothering me?

Well my dealer in Scottsdale keeps the Super Sport tire in 305/30ZR19 on hand at all times because a number of his Mercedes and BMW customers that is their OEM size, I don't hear any of them complaining either. It was the first set he put on a Z28

[Dr Chill]

Originally Posted by cliffy

Well my dealer in Scottsdale keeps the Super Sport tire in 305/30ZR19 on hand at all times because a number of his Mercedes and BMW customers that is their OEM size, I don't hear any of them complaining either. It was the first set he put on a Z28

Please tell me which MB or BMW use 305 width front tires.

The Z/28 is built to perform on the track. Wide front tires enhance braking and reduce understeer which is why they are found on this car. There are reasons why no other street vehicle comes with such wide front tires. It's not because no other manufacturer thought of irt before. The main reasons are a narrower front tire will maneuver better and not tramline. I'm happy that you love how your car drives with 305s, but it will drive better for street use with 275s or 285s up front, which, last I checked, are still very wide tires too.

As soon as I get my wheel/tire package, I will report back with my full impressions. Maybe I'll not like it any better than oem sizes. We'll see. I'm just going on what two supposed wheel experts have recommended. One was involved in the development of wheels for the Z/28 but ended up not getting the contract because he was out-bid.

[Dropspeed]

Originally Posted by Dr Chill

Please tell me which MB or BMW use 305 width front tires.

He never stated front, you jump to that conclusion on your own. They can use them on the rear of some AMG/M packaged cars.

Michelin does have a 295/35/19 Pilot SS available as well. It is of course -10mm in width but the OD Is greater.

26.2" 305/30/19
27.1" 295/35/19

This will give you just a hair under a 0.5" additional ground clearance and a slightly taller sidewall.

http://m.tirerack.com/tires/TireDeta...um=935YR9PSSXL

Matt

[johnr265]

Originally Posted by cliffy

Just go to your SELLING dealer, give them your VIN, and get their best price, and they will have to add in the core fee of $50. Takes 2 weeks to get them

Mine were $617 plus 50 each plus sensors. Makes no sense to fool around with custom rims and pay $800 - 2000 each. I think the stockers are the best rims in the world for the car for the $$

19" Michelin Super Sports are very common in the size we need. They are OEM on some Mercedes and BMW and are about 340 each at Discount Tire. For me they are the best all around street tire for weather above freezing. I don't take my ride out in snow

Out of curiosity, how long ago did you get your wheels? When I called my dealer, even with my VIN number, he was unsure he could get them at all and offered no discount off the $895 list price.

Dr. Chill, can you tell us what wheels you decided to buy and how much they cost? I have already purchased a second set of stock wheels/tires second hand for the track but might want to get a different set for the street and rain.

[APT]

A few online Chevy parts suppliers are advertising OEM in low to mid $600's + $50 core charge per wheel. My car will be primarily for the track, but definitely ordering an extra set of OEMs w/ Michelin PSS for street use.

[X25]

Originally Posted by APT

A few online Chevy parts suppliers are advertising OEM in low to mid $600's + $50 core charge per wheel. My car will be primarily for the track, but definitely ordering an extra set of OEMs w/ Michelin PSS for street use.

Including the core charge + shipping, my total cost was $2499.