Ok im considering new wheels and sticky tires. i figure if i get new wheels i might as well go with light ones. The problem is the more i look at mu car with the s-lites the more i like them (i enjoy the oem harmony). So i ask you the people of NAM how much of a differnce do lightweight wheels make?

thanks
Jonathan

 

I was just about to post a topic asking a noob question which is sort of in line with this thread. Can someone define the term "unsprung" weight for me? What exactly does the "unsprung" mean? I've just been thinking about wheel and tire weights in basic, dead weight terms, but didnt know if "unsprung" was referring to something else.

To answer 00zero, I basically understand lighter weights to translate into better acceleration, braking, and fuel consumption, but cant be more specific/scientific than that.

 

Unsprung weight just means weight not supported by the car's suspension. Tires and wheels are the most significant piece. As as they are also a rotating mass, have a greater affect on acceleration and braking.


That said, I went from Slites to Xlites, shedding about 6lbs* per corner and I can't say that I felt a night and day difference.

*Slite tires were well worn, X lites were new

 

Not much, unless you are carrying them in your arms.

 

if you are doing normal street driving then you prolly won't notice. but, you will on the track or autoX esp if you combine them with lighter than runflat tires. also the level of weight change makes a difference, i went to 13lb wheels which is a huge difference, and the times showed it

 

Lighter wheels will mostly improve handleing. Reducing the unsprung weight will improve the dynamics of the car. Unsprung weight refers to anything that basically does not sit on top of the springs. The springs are what carry the entire load of the car. (shockS are just used to dampen the motions). So unsprung weight is most of your suspension parts, brakes, and wheels. The suspension is designed to carry the weight of the car, but all the unsprung weight is at the mercy of physics. The less weight, the better the car will handle.

 

the stuff above the springs is also under the control of physics, but it's controlled physics.

 

cool thanks for the info!

 

Do a search, this topic has been discussed many many times before.

Light wheels help performance, acceleration and braking but they cost more and if too light can be prone to damage when hitting potholes at speed. Always drive carefully.

Smaller diameter wheels generally weigh less without too much added cost. The larger the wheel the more it can weigh.

See also
https://www.northamericanmotoring.co...ad.php?t=95865

15x7 and 16x7 are viable rim sizes
205/55-15 and 205/50-16 or 205/55-16 are good tires.

17x7 rims and 205/45-17 or 215/45-17 are OK.

Try putting on heavy work boots and run around your block. Then put on light running shoes and run the same distance. You might notice it takes much less effort to run in light shoes.

 

For a given, fixed budget, I think you'd gain more speed by spending more on stickier tires than on lighter wheels.

 

HUGE difference. 27lbs or watever R90 vs 11.5lbs comps is huge.
you will notice the instant you step on your brakes. where it seemed
it took forever to come to a stop is now a flash.

i really couldn't tell much of a difference acceleration wise but the
braking is night/day.

 

As far as acceleration goes, the harder you accelerate (change in your speed) the more difference it makes. So if you are gentle in speeding up then it isn't as noticable but if you stomp on your gas then you really get going quickly.

Same with braking, stomp the the brake and you'll stop quickly with light wheels.

For the budget there are many thoughts. Dollar for dollar- tires are a wear item in the short term and sticky tires especially so. You use them and they need replacement.

A good set of strong but light rims will last quite a few years if you take care of them and keep them out of harms way. This makes their investment a longer term benefit lasting through several sets of tires.

Since rims don't hit the road directly like rubber does it's the combination of the two weight wise as well as tire size/rim size and that's what you will experience.

So figure out your needs, pick the right class of tire to look at, pick the exact tire for your needs and budget then pick the rim size that fits the tire and your MINI.

Many people do almost the opposite. They have some wheels on the MINI and limit the tire size to fit the rims and then select a tire based on tire size. This is fine but much more limited and depends on your rim size. 16" wheels aren't bad but 17" wheels and tires are more oriented to performance and handling and less so to daily driving comfort but there can be exceptions.

 

Unsprung weight does make a difference as pointed out here many times. There are some great resources on the web to show the effects. Here are a couple of my favorites...

http://www.wam.umd.edu/~greghess/sizematters.pdf

http://www.tirerack.com/wheels/tech/...jsp?techid=108

http://www.nerocam.com/SCC_TAP.asp

I saw a calculator somewhere also that showed the effect of rotating mass for different diameter and weighted rims. Not sure where I put that link...