Josh R

iTrader: (1)

What will be better for handling. Its between 17in x 9.5 or 16 x 9.5, rather 16 but would 17 make a big difference?

AlkyIROC

Keeping the same tire height but increasing the diameter of the rim gives less sidewall. Although you will get less tire roll in corners, you'll have a stiffer ride because the sidewalls won't absorb the small road shocks.

Josh R

iTrader: (1)

so how much better for performance is 17in compared to 16in.

blyth18md

REAL good tires for the 17's will be worlds easier to find.

All things being equal(width for width, wheel make/model, contact patch) typically you want the smallest diameter wheel that will clear your brake package as it will weigh less than the larger wheel.

But the major wild card is the availability of the same tire in both wheel sizes. As first stated, most likley 17s will work out better for you 'cuz you'll find that finding tires worth a damn wider than 255 in a 16's is difficult.

275/40/17s are everywhere...

So I guess the real answer isnt what wheel is better for handling, but what tires do you plan to run? How wide What brakes do you plan to run? Can you suspension handle the extra weight (if in fact it does increase) of the new wheels and extra rubber?

Josh R

iTrader: (1)

well i have a stock iroc-z. Plan on running good street tires. Something around original or better tires. Stock brakes, only plan on changing the front to better rotors and calipers, but around same size. I really don't like 17's on pre 91 camaros. Same as i don't like pre 91 camaros lowered.

And your right i can't find 275/50/16s. The biggest i found where 285s, and the most common where 255. The 285s sucked though and would probably rub on the tie rods or wheel well. Will 255s fit on a 9.5 in rim?

blyth18md

what rims? 255 is on the narrow side for a 9.5. rim. And honestly if you're upgrading your brakes the 17s are the way to go. You'll have room to go and get access to better tires.

Josh R

iTrader: (1)

ok so ill give into 17s. To run 17x9.5 rims they require around a 0 offset, or -.25in. What rims other than the roh zs racing rims fit that. And how big of spacers can i get. American Racing has rims with a positive 3.75 so if I get a 4in spacer it should fit. Can i get 4in spacers?

The Project

iTrader: (6)

Need to know what rim you are referring to. 4" spacer seems too big. Most people run a 2" spacer depending on the rim and offset/backspace.

Need to know more before we can help.

91_5.7_TPI

iTrader: (2)

Blythe is right on target.
You can get 4th gen offset wheels and run 2 inch spacers or you can order wheels to fit your car. 4 inch spacers would scare me.
I think that 17x9.5s all around are a good idea for several reason. That's what I have on my car (when the stockers aren't). Try to find the lightest wheels you can. Heavy wheels won't help your cornering. By feel, my ZR1s with 275/40s are lighter than my stock 16s with 245/50s.

Josh R

iTrader: (1)

the rims i want are the 17x9.5 American Racing Torq Thrust II. They come with custom offsets. Basing my calculations on the roh zs racing wheels (which are 17x9.5) they have a -7mm offset. Thats bascially -1/4in offset. The american racing wheels come in -3in or 3.75in offsets. (Some other offsets too but those are what im looking at). The -3in stick too far out, and the 3.75in stick too far in. But if i get 4in spacers and use the rims with a 3.75in offset wouldn't that give me -1/4 offset, which is what we need... :P

BMmonteSS

That isn't 3.75" of offset, that's 3.75" off backspacing which works out to .75" of offset. So the 4" offset would be close to what you need.

As mentioned the tire selection for 16" wheels is nill, you'll be light years ahead with the 17's.

oil pan 4

iTrader: (1)

If you want tires check these out. My friend that works at yokohama tire got to auto cross these tires along with other tires once in some BMWs in the parking lot at the Roanoke Yokohama tire plant. He said if he had a car he would have a set of these for it.
http://www.tirerack.com/tires/Sizes....VAN+Neova+AD07
They are kind of expensive, but I plan to get a set of these or what replaces them when I pick up a set of 17''s.

91_5.7_TPI

iTrader: (2)

If you have the money, get the Toyo DOT R-compound tires. About $800 for the set, but that's a set of street tires.

blyth18md

Now if we could talk him out of such heavy wheels...LOL

91_5.7_TPI

iTrader: (2)

The TTIIs are, what, like 26 lbs per?

racing geek

iTrader: (5)

single stripe IROC-Z wheels - 23.X lbs each
dual striped IROC wheels - 21.X lbs each
spoked/wire GTA wheels - 16.X lbs each
I have no idea on the steel wheels, but then again, who would care.

The single stripe IROC-Z wheel is the heaviest stock wheel available for the 3rdgens. That's why when I need new tires, I'm just going to sell my two sets of those and get some 17x9 for the front and 17x9.5/10 for the rear.

Mike

Guest

I thought I recall weighing the single stripe IROC "rears" at 17.5 lbs. I could be mistaken, But I think not. I know fronts are slightly havier due to the offset. Fornts were like 18.5 (I am talking about the '87 factory IROC wheels)

TheScaryOne

iTrader: (3)

I got Falken tires on my last (emergency) tire upgrade, and I have to say, they stick. I can barely squawk the tires anymore. But get them wider than what you think you'll need. They run narrow. Between my Kumho 245's and the Falken 245's, the Falkens are noticeably more narrow. When I can afford the second half of the Falkens, I'm gonna get 255+ and have them mounted on the rear.

paul_huryk

You can't get a 275-45-16, which would be the equivalent to the 275-40-17. So its either a minimally wider 255-50-16 or jump to a 275-40-17, which is preferable.

I have modeled a street car scenario and came up with the wholsale conclusion that for every % wider a tire is (height being equal), you would pick up about 4/10% in lateral g handling and an increase in slalom (too hard to model). So if you can get .9g out of a 245-50-16 tire, going to a 275-40-17 should net about a .949g based on tires only. You can also pick up to 1% increase in handling by dropping the sidewall height by an inch (15" to 16" as an example).

91_5.7_TPI

iTrader: (2)

Cool information man. I'd read it increased the lateral Gs, but didn't know how much.

Guest

Not if that tire is not using it full footprint. How mnay suspensions on here are laterally bumped? Not any....but mine I would strongly guess. Don't use the misconception that wider means faster. Nor does the lower sidewall mean faster. Sidewalls have spring rate. too stiff can hurt just as much as to soft. A tire needs to be married to the suspension and the footprint be bumped for full contact patch through body roll and road imperfections.

Stephen

iTrader: (12)

There is always the BFG 295/50HR16 that fits the stock 16 x 8 wheels.

BFG specs the minimum at 8", so they are still within manufacturer tolerance. BFG gets away with them fitting a 8" wheel, because of the tall sidewall. I doubt they'd fit up front, but they really looked aggressive on my 92 RS. Gives the rear this "semi" Pro-Street attitude/look.

Can't say they would give the best sideways handling, but lets face it...I had a 150,000 TBI 305, with nothing but a cat-back & K&N filter. Oh the POWER!

One of these days, I'm gonna pull one of my 17 x9 Snypers with 275s front/285s rear & weigh them against my 245/50R16s on my original GTA gold crosslace wheels, & see how they stack up in the weight category.

Flip 2

iTrader: (1)

C5 Thinspokes:
front/ 17 x 8.5 = 18 lbs
rear/ 18 x 9.5 = 20 lbs

Lonnie P

Going to 17's made a world of difference on my car.

I used 17x9 w/ 6" BS. This required a 1/2" spacer with stock brakes & a 1/8" w/ C4HD brakes. Tie rod is very close to the wheel, but they are tucked under the car well & 275/40's only touch the plastic wells with the steering at lock. 9.5" wide would stick them outward more & possibly cause clearance issues depending on tire size, ground effects etc.

The reason I tucked them is to get as much tire possible without interference. If you want it to handle, stuff some tire under it & run as much backspace as possible.

The shorter sidewall added response & made it much more fun to drive. I'll never put 16's back on it.

paul_huryk

If a car is aligned right and has minimal deflection, you can get most of the tire in use, whether it is a 275-40-17 or a 245-50-16; both are effective on a third gen (or 4th gen). More surface area means more possible grip all else being equal, think of the difference of going from a 215-65-15 to a 245-50-16; the same is true from the 16" to 17".

Of course every tire sidewall has a spring rate, common knowledge. I'd be the first one to suggest a 275-45-16 if they made them, but since they don't a 275-40-17 is a good tradeoff.

I'm sure a few of you had read the article a while ago where Hotchkis did up a suspension on a third gen and picked up something like .04g just from going from 245-50-16 to 275-40-17 with the same exact suspension; slalom improved even more. And their stuff isn't anything but one step above stock.

racing geek

iTrader: (5)

Actually I never heard of the article. Would you mind posting a link to it or scans of the article?

paul_huryk

I'll have to look through my extensive magazine library... But I know its there

Stephen

iTrader: (12)

Do you know what issue it is in?

paul_huryk

Probably from a few years back. I might have to look through 300 magazines to find it...

Stephen

iTrader: (12)

My point was....By sharing the issue info, somebody might be able to spare you from the time, looking through 300 magazines.

For example...I too have a "small" collection, all the way back to the 70s.....We could help locate it, if the search was narrowed down.