17" S-Spokes vs. 14lb 16" wheels G-TECH'd!

[Garfield]

Here's the results:

All testing was done in the same location, 78 degrees ambient, same direction, 3 runs each

I made the comparison even more accurate by swapping my father's 17" S-Spoke wheels on to my car instead of driving two different cars.

17's
-----
0-60mph = 7.37, 6.74, 6.85 seconds
60-0mph = 127, 125, 133 feet

16's
-----
0-60mph = 6.57, 6.67, 6.52 seconds
60-0mph = 115, 111, 113 feet

Interestingly, but not surprising, it took more power to launch the 17/run-flats. I was launching the 16's around 3200rpm to get the perfect run while it took about 4000rpm to launch the 17's. It's obvious to me that the rotational mass was the factor to get moving quicker (this is also why the first run on the 17's was significantly slower, it bogged a little at just above 3000rpm).

I ran the 17's first to ensure that brake fade would not favor the 16's. Turns out the brakes cooled plenty in the tire change, although they were very hot when I changed after I was finished.

It is VERY easy for me to now see where the magazines could get higher 0-60 times. I've launched this car MANY times and it's well broken in, two factors that magazines do not have right now.

I was extremely happy to see the 111 foot braking number, that's quite impressive.

Again, take these numbers for what they are, a comparison via a G-Tech.

[noahe]

Great empirical data. Thanks for going to the trouble of doing that for us lot.

So, without a doubt it makes a difference. The car magazines would go nuts. Racers would switch rims. My friends would rave about the difference. For my purposes, that is not significant enough to warrant the asthetic, monetary and convenience losses to bother changing rims.

But yes, those numbers are compelling if you race.

[HarryHBMCC]

The best 0-60 times are only a quarter second better which would matter in a race but not much on the street but the braking numbers are impressive, more than a (MINI sized) carlength better with the lighter wheels. In this case it is an 11lb/wheel difference which is considerable. The difference likely would not be as noticable with the heavier X-lite or 5-spoke 16" wheels.

So how fast can you change the wheels now? It sounds like you are training for the Safari rally next year (when is the AWD S coming out?) ;-)

Harry

[fred-guido]

Very Interesting! I think the 0-60 times are not significantly different around 0.2 seconds slower for the 17's (throwing out the high figure)or about 2% slower. But the braking distance was a little more significant at about 15 feet more for the 17s or just over 10% more. Both are still quite good I think for a car that costs 20K! So I go with the group that think that the difference is not large enough to be the only factor in getting rid of the 17s. Each to his own!

[macncheese]

If .22 in the tenth isnt a significant difference, what is? .22 in the quarter mile is about 4 car lengths (maybe 5 MINIs ). 4 car lengths is a pretty sizeable distance on the track or the street.


--
Cheese

[BruceK]

Thanks to Garfield for performing the tests and posting the results.

I must say however, that the wheels are not the only variable here, everyone seems to be ignoring the tires themselves.

I would agree in the acceleration runs, the wheels probably account for most of the difference, but in the braking tests, I wonder how much can be attributed to the differences in traction between the standard Cooper S 'road' tires and the special 'auto-x track' tires?

[Garfield]

This is true Bruce, but they aren't autocross/track tires, just VERY sticky street tires. But, in doing this test, I definitely think the compound of the tires isn't that far off. The Pirellis are definitely soft, just not quite as soft as the Azenis'.

I can assure you that if I did this test on my Hoosiers I'd knock another tenth off the 0-60 and 5 or so feet from the 60-0.

My point would be that it's enough of a difference to warrant a change to a stickier street tire and lighter 16/17" wheel. There are plenty of 17's that are less than 20lbs.

These tests still can't show the quicker reaction the lighter wheel/tire will have in the bumps, that's still going to be the most significant difference.

[toofast]

Quote:

Originally posted by macncheese
If .22 in the tenth isnt a significant difference, what is? .22 in the quarter mile is about 4 car lengths (maybe 5 MINIs ). 4 car lengths is a pretty sizeable distance on the track or the street.


--
Cheese

I agree 100% the differences are substantial. I will not downgrade to 16" wheels though I will upgrade to ligher 17" OZ or BBS. Actually with the big brake kit Im going to install my 0-60 times may suffer some, but hopefully the extra 40 hp of the Works kit will displace some of this lost performance!

TOO MUCH IS NEVER ENOUGH!

[noahe]

Quote:

Originally posted by macncheese
If .22 in the tenth isnt a significant difference, what is? .22 in the quarter mile is about 4 car lengths (maybe 5 MINIs ). 4 car lengths is a pretty sizeable distance on the track or the street.
--
Cheese

Oh, it IS significant. I readily admit that. The street-racing community would go nuts. An enthusiast would be happy with the gains. But I'm satisfied enough with those numbers to stick with what I've got, as a daily-driver car...

Basically, it would have to feel like a different car, for me to warrant paying for better, lighter, (uglier) wheels, without the psycological comfort of run-flats. Since I like whipping the car about at around 3/4 of it's capabilities, comfortably racing around with a good margin of safety - and avoiding the ragged edge of top-end performance, I don't think a light wheel retrofit is in the cards for me right now.

I like looking at the numbers. I like knowing the facts. I like knowing what the car's potential is if I upgraded these items - but I'm not likely to change anything.

[macncheese]

Noahe,
If you go by too fast, people cant drool at the car.


--
Cheese
every moment frontin and maxin
chillin in the car they spent all day waxin
leanin to the side but you can't spead through
Two miles an hour so everybody sees you

Name that tune.

[Garfield]

That is certainly very logical Noahe.

The only difference I think most people would notice is 1)starting from a dead stop is definitely easier and 2)going around a turn and hitting a bump is much more comfortable with the lighter wheels.

If I didn't autocross, I would still change to something similar (if not the same), but I really put the performance a good step ahead of looks. Don't get me wrong, if I didn't care about looks at all, I wouldn't have gotten it striped.

[AidenL]

How do the R90s compare weight wise to the S spokes and the X lites?

The braking distance improvement is scary......could be the difference in hitting someone or not !!

[MINIMiller]

Quote:

Originally posted by Garfield
Here's the results:

...
17's
-----
0-60mph = 7.37, 6.74, 6.85 seconds
60-0mph = 127, 125, 133 feet

16's
-----
0-60mph = 6.57, 6.67, 6.52 seconds
60-0mph = 115, 111, 113 feet

....

Garfield,
Thanks for the experimentation and posting of results. Please specify the make and model of the 16's and the tires you were running.

Thanks.

[RickB]

I've inquired with my dealer about swapping the S-"Lites" for R90's; are the R90's significantly lighter? I'm not real high on the styling, but if it saved a few pounds per corner, I might do it. How much lighter are conventional hi-perf street tires vs. the run-flats?

[noahe]

Quote:

Originally posted by macncheese
every moment frontin and maxin
chillin in the car they spent all day waxin
leanin to the side but you can't spead through
Two miles an hour so everybody sees you

Name that tune.

Song: Summertime
Album: Homebase
Artist: DJ Jazzy Jeff and the Fresh Prince.

Not really my cup of tea, but my younger brother once played that album 900,000 times at the cottage one summer, sitting in the boat. Sound carries... Especially when it's just from at the dock.