Everyone talks about the weight savings of 16" vs. 17" wheels but I figure if you go with the same overall wheel/tire diameter, the weight you save on smaller wheels you will be making up with the added weight of the larger tire... no? I do understand the more comfortable ride but not the acceleration/braking advantage. Can someone explain.

 

the s-lites i believe are the heaviest rims mini offers for our cars.

the rims alone arent to blame. the runflat tires also attribute to the added weight. Rotational weight is a factor in handling. This is why the aftermarket often markets lighter weight rims as an upgrade.

16"s are a good balance between comfort and performance.
Even though the overall wheel/tire diameter is the same, the larger/softer sidewalls actually lower your car about .25". You'll actually ride lower in 16's than 17s too.

I am in the process of upgrading to 15" Konig rewinds which are lighter and hopefully more responsive off the line than my heavier s-Lites. I'll report back when i install them this weekend if you'd like.

 

You are going to love the Rewinds. I just switched over a few days ago and the difference is amazing!

 

The idea is that an inch of wheel will probably weigh more than an inch of tire. In other words, the combined weight of a 16" wheel and tire will most likely be less then the combined weight of a 17" wheel and tire. Of course, there are a ton of different wheels and tires out there, so it's possible to get a really heavy 16" setup and a really light 17" setup. But, in general, a 16" setup will be lighter than a 17" setup.

Using some numbers from edgeracing,

16" Toyo Proxes T1r tire - 19.4lbs
17" Toyo Proxes T1r tire - 20lbs
16" 5zigen Fn01r-c wheel - 14.5lbs
17" 5zigen Fn01r-c wheel - 15.5lbs

16" combo - 33.9lbs
17" combo - 35.5lbs

 

what you are gaining is a reduction in the inertial moment. by bringing the mass of the rim closer to the centerline of the axle, the amount of torque required to start/stop the inertia is reduced.

 

16in wheels will provide more acceleration then a 17in wheel as long as the over all diameter of the tire on the 16in wheel is smaller then a 17.

it works something like this...if you take a quarter and a dime and mark a dot along one of the edges. then roll each one of them the same amount of rotations, the quarter will go further then the dime. It has a larger diameter and travels more distance per revolution.

But to turn the larger wheel takes more torque then that of a smaller diameter wheel, which will actully hurt acceleration. As you saw the quarter would go further per revolution, a larger diameter wheel will also help your top speed increase (provided you have the torque and HP to go along with it) A 16 inch wheel with a smaller diameter is easier to turn due to the mechincal advantge it has, it does not take as much torque to spin as a larger wheel. But a smaller diameter tire hurts your top end speed.

Its just like the gears on a bicycle, its hard to start out from a dead stop in 10th gear, due to the fact you have to almost spin the pedals one revolution per tire revolution. where as with 1st gear you might rotate the pedals up to 5 times just to get the tire to turn once. You dont go as fast (top speed) but its alot easier to turn the pedals! the mechanical advantage of the lower gear allows you to create alot more torque. Same thing happens with a smaller tire, it spins alot faster taking less torque and providing more acceleration, but you lose top speed.

Ever go from large rims/tires to small ones, and notice your RPM's jump up?

this is only an example:

with 16's you might run 3,000rpm's at 70mph

with 17's you might run 2,700rpm's at 70mph

this allows more rpm/mph range before you top out and hit your rev limiter.

But for people who like quick acceleration (often autocross or track people) they would rather have accleration over top end speed. So you can exit those corners QUICK!

Also as stated above the theory is that 16's weighs less then a 17. This also helps with the acceleration of the smaller tire. Because it further reduces rotational mass and requires even less torque.

hope i didnt confuse you.

 

Well said.
Changing the dia can have a huge effect on gearing and driveabilty.

Months ago I sold a brake kit to a customer who also got a second set of hats and rotors. Now has both 11.75 and 12.2 parts. Simply becasue he knew the plan to alternate between wheel sizes for various tracks meant he needed to fit both wheel sizes!

That's my kind of competitor- out side the box thinking!

 

MINI MIZER!! what an awesome explanation!! I think it's the best one I ever read in NAM... happy motoring.

 

Expanding a bit on the gearing issues, one might wonder 'why' would this matter in a lot of cases?

Coming from hill climbs, the same applies here as on an autocross.

If the event size or shape dictates a top speed of 45-50mph for example then you'd not want to shift to 3rd gear for 50ft and back to 2nd gear the rest of the time. (same on dirt- more shifts means more lost time) Or you might find that the smaller dia tire allows you more rpm in 3rd gear and prevents the single downshift to 2nd for the one hard turn...

 

I agree with snid. The benefit to going with 16" wheels is lighter weight which gives the following perfomance benefits:
1. Better acceleration because of less inertia the engine has to spin.
2. Better road holding through less unsprung weight.
3. Better braking because of having less inertia the brakes have to stop. I know the owner of one of the major wheel distributors in the Houston area, and he is considering requiring a legal disclaimer for people who buy the very big diameter, very heavy wheels because it increases the stopping distance and brake wear, particulary on the typical >20" SUV fitments that are so popular.

When I originally went to my 16" Volk wheel & Toyo tires, the total weight of the combo was 29.3 lbs. 11.2 for the Volks, and 18.1 for the Toyos according to the manufacturer's specs.

All that being said, I think the 17" wheels look better on a MINI. I've even considered buying a pair of "non-performance" 17s for my car as a secondary set of wheels. It depends on where your priorities lie, and how important the performance benefit is.

John

 

I agree, its all preferance really, alot of autocross guys run 16-17's on the street and when they get to the track, they switch to some 13in race wheels. But 13's on the car for every day driving is not very practical as it runs the rpms up very high and kills gas milage.

so it all boils down to "form vs. function" and a happy balance between the two.

i love 16's but thats just my opinion.

 

WHAT?!

you shouldn't be driving a MINI.

16x7.5's look better on the MCS.

 

I'm surprised nobody said this yet: 16in wheels/tires, directly compared to 17in wheels/tires, are CHEAPER. I dare you to find a wheel that is more expensive in 16 than 17. Ditto for tires. If you're like Jermaine Dupree and the Jigga man, and "money aint a thang," then this reason doesn't mean a thang to you.

mb

 

In addition to faster acceleration, deceleration is improved. A long time ago, Brian Garfield did comparison testing to demonstrate the advantage of the 16" wheel/tire. Stopping distance substantially less with lighter wheel/tire. Further, the lighter the wheel/tire/brake system, the more compliant the contact patch is with the road. Improved traction/grip is the result. With reduced inertia, there is probably some impact on reduced gyroscopic effect and quicker turning. This has not been analyzed yet, though. I think larger width tire can be fitted under the Mini as well with a smaller diameter wheel/tire combo, unless the car is substantially lowered.

I have been pleased with the performance of the Falken Azeni 215-45-16 on the xlite wheel, though at an autocross recently a chick running 15" wheels and 225-45x15 Kumho's kicked my ***. Probably mostly driver skill.