Wheel/Tire Dillema on my 69 Camaro
 

Please tell me what you would do. I have a 69 Camaro with DSE Tubs (not yet installed), and DSE Quadra link rear. I am fighting with myself about what rear rims/tires to run. Here is what i am looking at:

19x12 On the back with 345/30/19

Pros: Killer Looks, Killer stance, Rims that i want are available in 19x12
Cons: Michelin is the only people making a tire of that size, may require a bit more modification to clear properly

or...

18x12 on the back with 335/30/18

Pros: Plethora of tire choice
Cons: The rims i want aren't available in that size. Either would have to be modified or new rims chosen. Rims/Wheels may not fill the well the way i like and look too much like a donuts.

or...

Any idea's?

Trev

19s look the best on a 67/78 due to the rounded wheel wells. Just check out Prodigy. On a 69, 18s look the best due to their squared-off wells. JMO

Personally, I like a little more sidewall on my tires. 18s for me.

-j

You saw how the 335 look with the 20"s IMO the 19's just look better than 18's but that is a personal opinion, i can get you a really good deal on the tires and possibly the wheels as well, give me a call and i wil look into it for you. i would go for the wheels you want and suffer on the tire as the wheel is the most important part

Blake I will give you a call tomorrow.

Trev

Actually I think 18's look the best on a '67-68 if you have the stance right..

see:
http://www.z069.us/68/exterior/speedway.jpg

The main problem with 19's is the performance hit you take and the cost/limited availability of tires.

I say go with the 18's.. look great and gain performance.

Why is there a performance hit with 19s?

Just my thoughts
 

Thought I would chime in on this duscusion. I like the 18's on a 69 but like 17's on a 67 and 68 just wish the tire size was slight taller then the 315 35 17. 69's seems to have more wheel openning in the rear to handle 18's. Just my thoughts.

nutsy -
The sidewall is so short on 19's. There is almost zero deflection (flex). The tire doesn't have as much chance to work as, well... a tire.

Correct me if i am wrong, but isn't there more sidewall on a 345/30/19 then a 335/30/18?

i would either go 18 or 20's there's a lot more tires for than 19's.and 19's look oddball to me.

It has to do with moment of inertia and it's not just that the 19" combo is heavier. It's that it's heavier farther away from the center of the wheel. As weight moves farther from the center it has a exponentially worse effect both on acceleration on and on stopping.

Think of a lever and the saying "give me a lever long enough and I will move the world"..

Here, for braniacs (unlike myself) this site should give headache.. lol
http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html

For people more like myself..
http://en.wikipedia.org/wiki/Moment_of_inertia
&
http://www.britannica.com/eb/article-9042379

Ok, so they are talking about bike wheels.. same principal..
http://www.canecreek.com/168.html

So to sum it up:
Polar moment of inertia
The resistance of an object to rotational acceleration. When the mass of an object is distributed far from its axis of rotation, the object is said to have a high polar moment of inertia. When the mass distribution is close to the axis of rotation, it has a low polar moment of inertia

Wheel weight is bad.. wheel weight farther from the axis of rotation is worse. That why a 20-inch wheel that weights 30lbs is far worse in regards to acceleration and braking when compared to a 17" wheel.. even if they both weighed the same (which I doubt they would) since most of the weight of the 20" combo is so far from the center point of the wheel.

Did any of that make sense? lol

It's not that you shouldn't run 19's or 20's or whatever. It's just that you should know the physics behind what you decide to do and understand what trade offs some decisions entail.

If you do the math all the tire side walls are about the same
335/30/18 is 26.1 tall and 13.3 on a 12 rim pilot sport
345/30/19 is 27.4 tall and 13.6 on a 12 pilot sport
335/30/20 is 28 tall and 13.5 on a 12 pilot sport 2
these are all Michelin tires
Pirelli has 345/25/20 @ 26.89 and is 13.43 on a 12.5 rim
and 355/25/19 @ 26.02 and 14.06 on a 13 rim
So it all depends on how you want it to look with the 20 you can tuck the rim up into the fender and the car is at the same height as having most of the tire showing with the 18" also if you already have a gear set for the rear then the tire size makes a differance as well. ......... oh yea the cost also the 18 are a little cheaper but not much

Mmmm....
 

Let me muddy the water just a bit. Stock on a C6 vette is 18's in the front and 19's in the rear. With run flats and a z-51 suspension get .95 on the skid pad. Run flats are pretty hard tire. C6 Z06 are running the same 18/19 combo but I believe it is a 275 up front and a 305 in the rear...it pulled right at 1.0 g.

I understand the physics of rotational enertia, even if I can't spell it, but on a street car I am not sure you would loose that much, but I have no practical expeirence with this. I will tell you to run as much sidewall as possible, you will thank me the first time you hit a pot hole you did not see. I have 18's on an 850 and I can tell you I spend most of my time looking for holes while I am driving.

I believe the hot set-up for track cars is an 18 in front and 17 in the rear

very good piont payton...sometimes I think people don't realize these are STREET cars....the majority aren't going to notice the difference in handling in a 19 verse 18 anyway

Im going to go out on a limb and say that there may be other influences involved in the 1.0g than tire size.

True, BUT that doesn't mean you shouldn't know what's going on. Making INFORMED decisions is what this is all about.

The worse thing in the world is for someone to slap on huge wheels and think it's the same as the smaller deal, just bigger.

18x12 335-30-18 pilots 68 convert looks perfect!!!!!!!

I might have four of those for sale.. lol

Ill take all 4 we go through alot of tires :D ( burn outs)

got the 19by12 19by10 combo on my 69 there are photos on a post somewhere

tire size
 

Damn True-

I agree 100% that tire size did not have an effect on the numbers the corvette pulled. I was eluding to the fact that tire technology has really advanced and it is possible to be great performance out of the bigger sizes. I believe that Dave Hill, head engineer for the corvette, stated that new tire tech has helped the corvette achieve its current results.

Steve-

What the hell? Tell me you are not going to change the rims on Penny.

I wasn't meaning you in general steve.....and I agree 100% with what you said...first time I had seen those links also, looks like you have been preparing for this question.....lol since it is asked so frequently :D

Steve you mentioned somewhere that you have Forgeline wheels. I am trying to order a set of Forgeline SP3P wheels in 18x12 with 5.5" backspacing and they say they can't do it. The best he can do is 18x11.5 with 3" backspacing which is not the look i am going for.

What kind of wheels do you have? Size and BS?

Trev

I will be running 345/19's on my '68. My answer to the inertia problem is just bigger brakes! I also plan on 285's up front. The ONLY thing that scares me about running these sizes is standing water. I don't like the idea of becoming one large ski. I say go for the 19's.

Mike

How will you handle the problem of only one tire available in that size?

I'll offer my two cents, on two topics. One, if you are going to run the car on the street and truly want to enjoy the ride, I'd go with as large a sidewall as possible while still hitting the look you are after width-wise. Two, the most importnat thing you can do to make your car truly awesome in the rear is to install a Lateral D three link setup! :unibrow:

Okay, so I'm biased... Honestly though, tires are SO good these days, you probably wouldn't notice the difference in performance between an 18, 17, and maybe other rim sizes, stressing performance. In terms of ride quality, the more sidewall you have, in general (depends a ton on tire construction), the better of you'll be.

One truly hard thing to do is to find a really good, huge tire for the bigger cars, like the 68 GTX we're doing, like yours, there are few choices for tires on this one. Aaack.

Mark

Current production Viper tire so I don't think they will quit making them anytime soon.

As far as sidewalls, 345/30-19 has 3.5 inches of sidewall. More than most any 18" tire anyone else is running so I feel comfortable with the ride quality I will have.

Mike

Good call, that is exactly the size tire I have settled on for the back of the GTX, plenty of meat all around. And they're cheap too.....NOT! Gulp, oh well, price of playing I guess. I saw Pilot sports, but haven't seen a whole lot of other options, including any R-compund tires which I'd prefer, big time. Anyone know of a set? Hoosier slicks come next, not sure the local law enforcement would let that go though!
M

Hell no! the wheels are one reason I bought the car.. lol

Just changing the tires to a stickier variety.. :)

I just ordered 335/30/18 in the Toyo competition tire.. oh, are you going with 19's? If so then your screwed.. I havent found R's in anything bigger than a 18..

To get "R" compound tires I know I will have to step back to 335/18's if I want to get serious on the track. Here is a question I have thought about? Due to the widthon the 345/30/19, how would it compare to a narrower "R" compound tire? Say a 275 or 285? I have wondered about the understeer the 345's would produce. Could they be balanced with a "R" compound tire up front only? If need be I will start a new thread on this issue.

Mike

Are the michelins really only choise for 335/19" ? :(

69 Camaro wheels
 

:lateral: I would go for the larger wheels, check out the Camaro that we are building now with 19X12.5 on the rear. http://www.feslerproductions.com/1969FeslerCamaro.htm, it is worth the extra work to get the larger wheels on there and if you have any questions on how we did it email me. I have two 69Camaros right now with this size in the back and they look sick.

Chris

Nitto also makes a 345/30R19
Specs for ya
http://www.nittotire.com/#index%2Etire%2Einvo

For 19" race tires, You can get 345/30/19 Michilen Pilot Sport Cup also.

Call Mike at MCC and get his rear frame rails and MCC BIG TUBS you get an extra 2 inches over DSE tubs! And run those big mofo's, its the only way to go:cheers:
Mario

Thread started Feb 13 2006:lol:

:lolhit:

Funny how 2 years ago people were asking about them and kinda Poo Pooing them, now we run them on most of our builds!

How about suspension travel?? With a 19 and a proper stance your travel will suck unless you do modifications to the back of the car or bag it an run like a donk down the road. I am pretty sure that not many first generation Camaro owners running 19’s or 20’s are big performers on the track unless the suspension was engineered around that tire and wheel package. I agree with Payton that a pot hole will be an enemy especially when the rim will take the hit because the suspension is bottomed out. I do however like the look of a well stanced camaro with a 19's. I really guess to have to weigh what you want to do to the car, and ask what you are willing to live with.