This afternoon I ordered my new wheels and tires from Alex at Tire Rack. I have a 2002 MCS currently wearing 46 pounds at each corner of S-Lites with run-flats. New setup is Kosei K1 TS 15" wheels (10.6 pounds each!) with ContiExtremeContact 205/55/15 tires (19 pounds each!) for a total of 29.6 pounds per corner. I am a little nervous going to a 55 series tire from the current 45 series but I imagine the handling of the non-runflat will be superior anyway. Plus, the ride should be a bit less harsh. I can't wait for the UPS truck to show up with my lighter wheels/tires.

Does anyone run this combination? What are your thoughts on 15" on an MCS?

2002 MCS DS/Blk - 15% pulley - Pilo CAI - Stainless Steel Brake Lines - Borla Street Exhaust

 

Shutterblade,
You should be fine. That's quite a jump and a good one for any MINI.
16.5 pounds x 4 wheels makes it 66 pounds but that equals loosing about 260 pounds of dead weight from the car.

I have the same light Kosei wheels for autocross but Kumho V710 205/50-15 tires for high performance. Weight is similar. Ride quality is good, I think you will like it. No real problem with the 55 series tires. 205 is a good width.
Having non runflats will be a real treat.

You will wonder why you didn't go lighter earlier!

 

How does 66 pounds in the wheels and tires get to equal 260 pounds of dead weight from the car?

 

rotational mass is roughly equivalent to 4 x

 

The first thing I noticed when I got my light wheels was the extremely
shorter braking distance and less effort needed to stop.

 

The net effect (on performance) of loosing 66 pounds in your wheels is about the same as loosing 260 total pounds from your car (not including rotating parts such as the wheels/hubs/rotors.

There are two types of weight in your car as you go.

The weight of those things that are spinning or rotating like the brake rotors, the hubs,the rims and tires. And secondly, the weight of everything else that is being dragged along. It takes lots of energy to move the rotating parts from a standstill so the more weight you loose in those rotating parts the easier it is to get going faster and stopping faster.

See
https://www.northamericanmotoring.co...ad.php?t=18265
https://www.northamericanmotoring.co...ad.php?t=36428

 

shutterblade, will you share the cost of your setup? I've been contemplating moving off my S-Lites to a 16" wheel. I'm running the 15" MINI wheels w/ Nokians for the winter, and it does make a big diff, so I'm actually considering going to a 15" instead (also budget rationale). Mebbe even keep my 15" (R81s?), get non RFs for them, and then get steelies for my Nokians next winter.

And Minihune, what the h*** are you doing up at 3AM? You a Wall Street person? I had a buddy who worked for Shearson that was up at your hour, finished by noon your time. Great schedule for the beach but terrible social life

TIA

 

I think that 3:00 am Tuesday on the east coast = 10:00 pm Monday in Hawaii.

Theo

 

minihune, thank you for the references. They were just what I was looking for. Intuitively, it would seem that loosing rotational mass would help acceleration (hadn't considered braking - that seems to be an additional benefit...). However, the 1:4 specifics were what I was interested in.

Out of curiousity, I wonder how many owners of CVT MINIs are stripping their cars to the bone? With CVT design limitations on adding hp and ft/lbs, dieting is the best performance enhancer available to the CVT.

Thanks again.

 

***sigh****here we go again.

FOR THE PURPOSE OF ACCELERATION NOT HANDLING:

if you go by physics, the MAXIMUM multiplier effect of removing rotational mass from the wheel is 2, which occurs when you remove the weight from the tire tread. that is, removing one pound from the tire tread is like removing 2 pounds from the chassis.

removing weight from the center of the hub has the same effect as just removing it from the body; the multiplier is 1.

just do a search here and on mini 2. you'll find a couple of threads giving you the physics derivations.

most wheels and tires are 1.6 to 1.8.

of course, if you don't care about physics, just use any number you want.

 

Actually, about a month ago, I tried a search using the phrase rotational mass and struck out. Then this thread popped up and I thought I would pose my original question here.

So, is the consensus a 1.8 multiplier for 15 inch wheels and tires and 1.6 for 16 inch wheels and tires? Or????

 

was $963.00 from Tire Rack - mounted, balanced and delivered to my door. The cost savings of 15" vs. 17" was pretty good - the same setup on 17's would have cost over $1250.00

 

Wow, you guys are really deep into this one.

Does it really matter what the multiplier is? I mean you took 16lbs off the wheels and know that it's an improvement. Does it mean anything that it's equal to 260 or 150lbs off the car?? You really didn't take that off the car anyhow...

I'm often asked "what's the best and cheapest way to make my car stop better?" Easy. Take out 300lbs of stuff inside it. But nobody wants to rip out the sun roof, stereo, sub box, seats, sound material...etc. Too bad because it works. But like the above example it's just not quite what we had in mind.

 

No, it doesn't really matter what the exact multiplier is although it sounds more impressive the bigger the "estimate" is.

If you want better performance then either you can cut the weight or increase the power.

Many of the places I've looked mention improved handling with lighter wheels/unsprung weight.
http://www.nastyz28.com/pthandle.html
Quote from Suspension theory:
2.) Minimize suspension unsprung weight for best handling. Unsprung weight is what is on the outboard end of the suspension - what is not being "sprung" by the suspension. This includes wheels, tires, brake components (rotors, calipers, drums) suspension arms, spindle, rear axle and associated brake components, and the leaf springs. By reducing unsprung weight you are reducing mass in motion in the suspension. Less weight moving up and down means the suspension can react more quickly to changing road surfaces and keep the tires planted on the ground better. This all equals higher acceleration traction, cornering traction, and overall better handling and road feel.