84Coyote

The title pretty much says it. I'm finally gonna be able to put my rims on. But I'm wondering if there will be a performance loss, and if my indicators will need adjusting. I hope it will be fine since the wheel itself will be almost the same diameter all together. Thanks

NoWorries

I think you will see an improvement, as they have to be lighter than the stock "turbine-style" wheel you've got on there now.

Impala SS's have the coolest looking wheels stock, but its insanely heavy, its pretty common that although Impala guys love the way it looks, the ones into racing put a lighter wheel on for racing, at least.

65Z01

Go to Tire Rack and get the diameter of your current tires and that of the new ones. Take the ratio to see how the torque will change and how much speedo error will be introduced, if any.

As mentioned a reduction in rotating mass will enhance performance.

my02cents

Actually there will be NO difference (besides weight) if you do it correctly. There is a formula for making sure you have the same tire diameter in the end. If you have 255/50/R16's that would be = to 255/40/17's... etc... I am not sure if that example is correct but there is a calculation you can make. I am sure the tire guys can help you. :)


[Modified by Red84CrossFire, 1:09 PM 2/26/2002]

84Coyote

So anybody know if the 97 rims I plan to put on are heavier than my stock rims? They've got the Goodyear Runflats on them.

Mr Mojo

Runflats weigh more than standard tires.

Stock C4 rims with non runflat tires-17x9.5 with 285/40ZR17 weigh 47 lbs
17x8.5 with 255/45ZR17 weigh 46 lbs.

96LT1

You definitely want to dump the run flats. The stock 16" tires are 26.1" in diameter.

The 275/40-18s that are stock on the '97 are 26.7", so you will loss a little of your gearing. On the other hand you could replace the 275's with either with 265/35's or 285/30's with diameters of 25.5" or 25" respectively. The 285's would give you a little more out of the hole.

84Coyote

Gosh Darnit. Will the loss be noticeable? I hope not. Dang-it. I'll check out the tire rack. And for now I'm going to have to stick with the run-flats. Their all I got

pzoom

Here is a link to a program I wrote a while ago to calculate tire/wheel combo changes. It should help.......
http://www.geocities.com/koottung/tirewizard.html

84Coyote

In the rim calculator section I inserted 255-50-16. I told it to calculate. For the diameter of the 16-50 tire was 26.039. The diameter for the 18-40 was 26.031. It stayed 0 all the way across the board. But it also indicated that the 18's will have .6 inches on the 16's. Is the 0 good? Maybe you could run the numbers and explain it to me a little better.

I'll have 275/40/18's on the rear as compared to the 255/50/16 now.

92TripleBlack

You have two choices. The 275/40/18 is 26.7". The 255/50/16 is 26" and the 275/35/18 is 25.7". The last size is slightly smaller than the original. It would actually be equal to the same range as the original with some wear on it. You would have slightly better acceleration, much better handling, slightly harsher ride, and be a little lower. Your speedo will read slightly higher than you actually are going(1-2 mph at 70 mph). I would go that way. Michelin Pilot sports can be had in that size as well as others.

Texas CE

It works just like the gears on a 10 speed bicycle: Larger gears yield better acceleration but reduce top end, small gears increase top end but reduce acceleration. Don't forget to recalibrate your speedometer.

MagRed_04

I did not notice any difference... :yesnod:

JK

84Coyote

So with the bigger wheels in the rear, will my speedo indicate I'm going slower than I actually am? How do I recalibrate it?

BBA

I broke one of my 16" wheels, so I bought a set of 17" wheels.
It only took me about 3 months to get 16" wheels on it again. The 17"s beat me and the car to death...and they spun too much.

The funny thing is my car handles so much better with the 16" wheels it's not funny. Yet my bud's 96 with the same 17" wheels rides like a cadillac. There is a lot to be said about tuning a car for the tires/wheels it has on it.

Can anyone tell me a down side to 16" wheels? Please don't say traction or handling...as the 84 pulled over 1G with 16" wheels that weren't even as wide as the stock size on cars with 17"s. I know the 16"s hook better also...those Kumho 17"s were like walking on bananas to my L98!

h rocks

:confused: :confused: Bad handling, spins too much, beat you and your car to death???? There's more to it than simply rim diameter BBA. Handling should improve all things equal. Spins too much, ok maybe if you're using a 35 aspect ratio tire, and talking about drag racing. Beats you to death? Maybe if you had those 35 tires installed, they definitely will firm up the ride, but then should also improve you handling>

UDLUV12

Michael,

Here are a couple of sites that might interest you: (posted earlier by another forum member...can not remember his name).

To find your tire diameter, go to: http://www.miata.net/garage/tirecalc.html

Input engine RPM's at this site: http://www.anglefire.com/fl/procrasination/rear.html

Cool sites!!

VetteNoob

Cool site (1st one). The 2nd one takes you to a dating site. :eek: The first site shows the following:

255/50/16 775 revs/min, dia. 26.0in
295/40/17 767 revs/min, dia. 26.3in

Speedometer reading with 17" tires is 1% too slow, when speedo reads 60mph, you are actually going 60.6mph. Does that seems like a close enough match without having to have speedo adjusted?

BBA

h rocks, what year do you have and what tires are on it?

RocketSled

[QUOTE]Actually there will be NO difference (besides weight) if you do it correctly. There is a formula for making sure you have the same tire diameter in the end. If you have 255/50/R16's that would be = to 255/40/17's... etc... I am not sure if that example is correct but there is a calculation you can make. I am sure the tire guys can help you. :)
[QUOTE]

Roger that. I've got a set of 16 inch weekend warrior wheels with slicks...they're almost identically the same height as the weekday 17 inch wheels with the Potenzas on 'em.