I may or may not be picking up some ROH ZS and they only have them in 17", is there anything wrong with going 17 on front and back on our cars? More expensive tires? Suspension? THanks.

 

tires get a bit more expensive every time you go to a bigger rim, they take a huge jump at 18 too. Other then that it wont make any difference. Also i think performance wise 17" rims are optimal for our cars due to the solid rear axel so you should be set.

 

you'll love them over the 16" slightly less straightline acceleration due to a thinner sidewall but that can be curbed with drag radials if needed. the larger rim will allow for larger brake upgrades in the future which is nice should you ever decide to go that route.

while the rim itself may be a little better overall you'll like them alot more then the smaller sizes.

 

The larger the rim size, the harsher the ride (given the same tire diameter) due to a shorter, stiffer sidewall. But if you wanted a soft, cushy ride, you'd probably drive a Cadillac.

Tires are more expensive, but not like they used to be. IMO, 17's are the perfect size for a Thirdgen.

 

im gonna be in the same boat. i think this year im gonna buy some boyd coddington rims. i dont know whether to get 17's or 18's too many cars come stock with 17's. i think 18's might look cool. i wanna go 18x8 in the front and 18x9.5 in the rear. does anyone knoe what tires would run for them .

 

you would be better off going 9 or 10 in the rear seeing as how very few boyd rims or 2 piece billet wheels for that fact are .5 sizes.

tire prices depend on brand and style as well as rating....personally with a dished wheel 18's look like 17's. if you go with a facemount cast wheel like a zo6 and such then 18's look like 19's. the ride isn't bad with 18's but you will need a good suspension and the right tires.

 

these are the ones in want , kandied they come in 18x8 and 18x9.5 .

 

Generally, the bigger the rim, the more it weighs.

 

???? typically a .5 size is rare in a custom billet wheel but that's fine if that's what you can get. 9,9.5,10 all can work for the application!

 

Well first off with 17" rims they are bigger so are going to be heavier and slow down your acceleration. Tires are more expensive too. But on the other hand 17s will vastly improve your handling over 16s(if u go wider) and your braking performance will icrease as well.

 

17"s can help in all feilds.......... u just need the right tires, plus they make the car look awesome

 

How come every drag racing team uses either 14in or 15in rims. I would expect everything they do they do for performance. So would the smaller rims be better?

 

less weight and more sidewall

 

the less rotational weight the better....that's the down size to large brakes.

 

Do taller wheels make any difference in handling, if the wheel is the same width? Same brakes, same tire width, same overall tire diameter.

 

yes, sidewall size does effect handling, i know that some people disagree with me on thsi point, but i am going to say it again.

almost every sucessfull road racer i know, says run the SMALLEST diameter wheel you can, that comes in the width you want, and will clear your brakes. of course a 18x11 with proper tires will outhandle a 16x8 wheels. there is 3" more with, plus the added track width (depending on backspacing of the two wheels). 16x11 vs 18x11 is another story, i would og with the 16's as long as it cleared my brakes, and i can get the tires i need in that sizing.

 

I read an article a couple of years ago where a magazine took 16x8, 17x8 and 18x8 with the same tires and ran them on the same car on Mid-Ohio. The 18" wheels were the slowest. The 16's were a like a tenth faster than the 17's, but the driver liked the turn-in of the 17's better. They felt that the the lighter weight of the 16's made up for the better handling of the 17's and that the 18's were too heavy and had too little sidewall to work in the imperfect world of a race track.

 

well tires are better now days and if you have the cash 18's can be lighter....

it all depends. cast for cast and cheaper tires i'd stick with a smaller rim as well for performance.

 

Exactly what I was thinking about. Since Thirdgens don't ride so well stock, adding a raciing suspension and low profile tires will make it worse. Throw a 18" wheel on it and its unbearable - enough to make the handling worse due to the car skipping around a lot. I would say a 275-40-17 tire on a 9.5" wheel is about as big of an improvment as far as bang-for-your buck goes, although a 315-35-17 in the rear is better, it may bottom out on lowered cars. Anything 18" is for show only, it won't improve handling one bit.

 

it did on mine.....i love it and wish i had 19's.

i suppose the 19" supercars and domestics using 18 and 19" wheels are only for show but they seem to work well for them too.

if it's a street car and you can afford it enjoy it, the look nicer and work great. so long as your suspension is up to date they ride fine.

 

They need them to clear the huge brakes on those cars. Also notice that the wheel diameters are larger - some as big as 28". Its a me too type of thing - they have it on theirs, so we need it too (on ours).

 

well i suppose you could look at it anyway you want. just preference but i know that my times weren't hurt going larger.

 

what times ?

do you have times around a road course on the same day with the same tires, and 2 diffrent wheels? how about an auto-x on the same day? when you say it has no effect, i assume you are talking about your 17's vs 18's on bfg drag radials? and comparing you 60' times.

Kandied -- i'm not trying to start a flame war about this, as you have accused me of before (do note that you were the one who mentioned money though ). and this is not personal at all, do a search for my name back a couple of years. you are not the first person i have disagreed with about tire sizes. my story hasn't changed, i am sharing my experiance, just like you are.

but what tire combination you use really depends on the cars use. with my suspension, i would not think of running something like an 18x11 wheel on the street, the car has such tight turn-in, and reacts so fast as it with 15" street tires on it. racing it gets 16x8 on race tires, but at that point i am dealing with a closed course.

 

go find a hobby that you know something about.....

 

i'm really glad you responded with real good valid data about the above subject. thanks.

 

the kandy got to his head dude.

 

A taller side wall may be used for more adjustability with air pressure. Basicaly be able to change the spring rate by lowering or raising the air pressure a few pounds. I'm not talking about the weekend warrior that beats on his street car a couple weekends out of the year, but the profesionals. Plus it makes sense that a taller sidewall would keep the tire temperature down over a longer run. But then again I don't know anything about this stuff and a street car really wouldn't benifit from any of this with a taller sidewall.

My 2 cents.

 

Just FYI, F1 cars run 13 inch wheels and I believe nascar only runs 15's. I don't know of any mojor road racing or drag racing series that uses huge *** wheels. They're either just for looks or to clear big brakes.

 

well, F1 runs what they do for saftey reasons, the cars were just to fast, they had to slow them down, that is also why they run the tires with the grooves down them. and they can get away with a wheel that small, since they use that funky drum looking thing for the brakes.

the Le Mans cars do run large wheels, but they need them to clear the HUGE brakes those cars run.

 

Dewey is correct. When it comes to Road Racing, you run the smallest possible wheel diameter that you can get away with. Rotational weight is Ten times that of static weight. And the closer the mass is to the outer radius , the worse the situation becomes.

Lemans Prototypes, LMP900's and the old GroupC and GT1 Proto-types ran large rims for two reasons.

1) To clear the HUGE brake rotors that they use. 15" rotors the norm.

2 ) To lengthen the tire footprint becuase of class restrictions that limit rim width.

Porsche started doing this back in the 1980's when the FIA and IMSA tried to slow them down by limiting rim width. Porsche was dominating at the time. Since Porsche had the engine in the back and required a large rear tire footprint, this affected them more than other competitors.

Porsche's answer to this was to increase the diameter of the rim to enlongate the tire footprint and gain some of the traction lost through the narrowing of the width. Thre was no restriction on rim or tire diameter at the time. Porsche went from 16" diameter rims to 19" diameter rims in one year. And thus began the whole evolution of Plus rim sizing.

Without having to go into all the technical details of why.... that would fill hundreds of pages... the optimum aspect ratio for Road Racing tires is approximately 45 to 50% on steering tires and 55 to 60% for drive tires.

Anything below this is strictly due to limitations on rim sizes due to rules. Tradeoffs are made to the tire construction, in respect to aspect ratio, strictly to gain footprint area taken away by limitations in either rim width or by mandating a particular rim diameter.

Note: I was trying to find a link to some data on Michelins current F1 tire and it's sizing...but I can't find the stoopid linK!! Anyhoo..from memory....the front aspect ratio was around 50% and the rears were around 55%.

 

The only technical reasons (excluding stuff like bling factor and 'cause that's what everyone does) to go with larger wheel diameters is to clear larger brakes and because tire manufacturer's tend to give you more high performance choices in larger diameters. Sure, the sidewalls on 17's flex less and respond faster then 15's, but there is only so fast that the human body can respond. Many _good_ driver's can hold a set of relatively tall 15's at the limit and adjust for conditions. I don't know anyone that can do it repeatedly with 16's, 17's…. I tried this a few years back running Hoosier race tires at an autox, registered for 2 heats and tried the same width, same diameter 15's and 16's. The 15's I was able to "drive" on the edge, the 16's were like a light switch, I was either there and safe or spinning off the course. My best run with the 16's was just about 2 seconds slower then my worst with the 15's.

So what's heavier, aluminum or rubber? Look at the stock wheels. There are some 15" firebird wheels that are very similar to the 16" wheels. I own both. The 16's have 245 50 16 goodyear ZR's on them, the fronts weigh 58# each and the rears weigh 54# each (the only thing that I can think of is that the hub on the front wheels is about ¾" thicker). The 15's with a tire that is the same width and height weigh 39#, and I'm running stock size, 215 65 15's Goodyear GT+4's on the front as skinies on a set of these which weigh 34# each. That's 78# difference between the sets. Rotating inertia causes anything rotating to effect acceleration, deceleration, handling… at roughly 4x the rate that stationary weight in the vehicle. The difference between the 2 sets of tires is just about the same as driving or racing with an extra 320# worth of passengers in the car.

Add that in the real world streets aren't smooth and perfect like most road courses… taller sidewalls deform and absorb road imperfections, shorter sidewalls do not.

FWIW, I've tried a number of combinations on stock f-body wheels (I've owned 4 f-bodies here, and have at least that many sets of wheels floating around to try stuff with) are the 15x7's with 235 50 60's on the front and 255 60 15's on the back. This would easily out handle anything I've tried on my 16" formula wheels or my 17" WS6 wheels (on my 97 WS6). What I want to run sometime is 15x9's on the front with 265 50 15's and 15x10's in the back with 295 50 15's. I'm betting that this would be pretty close to an unbeatable combination with some good wheels.