Hello,

My heart desires 18" inch wheels, but I'm worried about the rotating mass of the wheel being an inch further out from the center. Do Run Flat Tires on a stock Mini 17" inch wheel create more or less rotating mass than an 18" inch custom wheels? I would be buying much lighter weight wheels than stock, what is the weight difference between stock versus a lighter weight 18" wheel?

Thank you!

Systemlord.

 

What are you using your MINI for?

Only street driving?

As long as you can minimize the weight of the 18" wheel and be careful about which tire you mount you can do better than an OEM 17" wheel and runflat tire in handling and performance.

Trouble is most 18" wheels are heavy, the lighter ones are going to be more expensive.

How are your roads? Any potholes and hazzards? If so then you don't really want to run 18" wheels and 40 series sidewalls or you will have to be very careful or risk damage.

The lighter the wheel and tire, the less the weight is at the farthest from the hub, the better for handling, performance, braking and acceleration. Less energy is needed to move that spinning mass from a start or to change direction.

Just changing from runflats to non-runflats helps a lot.

 

+1 to all of what he said...

lighter wheels and tires will also improve gas milage

 

I was surprised how much of a difference going to lightweight wheels made on my acceleration. But yes, be careful of potholes. Very very careful. Those are some mighty thin sidewalls!

 

Yea in the past.. Jumping from 16" wheels to 18" wheels was a huge loss in power, braking, and suspension rebound...

Handling was better due to the shorter sidewall..

 

Darn, SoCal is littered with very good roads but also has some bad ones as well. It seems as if I'm going to have to go 17" wheels, what weight wheel is considered very light weight for a 17" wheel? I have nothing to compare with since I have not a clue as to how heavy my stock Mini 17" wheel really is.

I happen to be a my brothers house till tomorrow and he has a quality weight gauge, can somebody tell me the torque specifications on the wheel bolts?

 

The Pirelli P Zero Run Flats (205/45-17) are 22lbs if the website is correct, this means that my Mini wheels are 21.14 pounds. Compare that with the Breyton Race GTS-R 17.6lbs, will I gain any faster acceleration with these wheels with and without run flats?

My rotors on the other hand are now deep dish rotors, changing them soon! This explains all the break dust that I have been complaining about, perhaps it's worse than normal. They are below spec, I have the Mini Sport drilled and slotted rotors at home, all I need are the pads.

Let's see if I came close, I used 85 ft.lbs, it could also be 103 ft.lbs

 

Torque specs for your wheel lug bolts is 103.3 ft-lb. (140 Nm).
Lug bolts are M14x1.25

The look of a bigger wheel diameter looks more aggressive and the sidewall looks minimal which is popular. However a 205/40-18 tire is not as forgiving but there are some exceptions, usually with a higher cost.

17x7" MINI OEM wheels from about 2007+ weigh about 22 to 24 lbs each.


A sample 2007 OEM 17" wheel on a Cooper S is an R104 Crown Spoke rim,
it weighs 22.7lb (10.3kg) each and has a 48mm offset.

Before you decide on a wheel you should not forget to think about tires. Since you are in a mild climate you may want to consider a Summer tire you can use year round. You determine the budget for both tires and wheels and that will set the limits on what you can begin looking for. The more you pay for wheels the less you have for tires which can be a very bad thing.

I suggest that you prioritize the tires over the wheels which gives you some idea on a tire budget range then you can look at wheels that are within budget with the lower possible weight and with a design and finish that you can live with.

Assuming you want a very comfortable street tire that has excellent handling in both dry or wet weather, first place to look is in the Max Performance Summer tire class. The common choice is the Michelin Pilot Super Sport for good reason. It really does everything well, however with a treadwear rating of 300 it will tend to wear out faster than an All Season tire and it won't be as grippy when on a track as an Extreme Summer tire like the BF Goodrich g-Force Rival.

If you budget will allow the Pilot Super sport does come in-
205/45-17 $179 each, 20 lbs, tire diameter 24.3" (OEM size)
215/45-17 $145 each, 21 lbs, tire diameter 24.7" will fit OEM wheel and suspension though slightly taller than OEM. Good price.
205/40-18 $170 each, fits rims 7-8" wide, 20 lbs, tire diameter 24.5"

Some sample wheels from tirerack that will fit your MCS- (et= offset)
In 17"


Sparco Asetto Gara Bronze or Black painted finish
17x7" $143 each, et 37mm, 18.3 lbs each


Kosei K1 TS Silver painted finish
17x7" $196 each, et42mm, 15.0 lbs each


Enkei Racing RPF 1 Silver paint finish
17x7" $230 each, et 43mm, 14.6 lbs each


Breyton Race GTS-R Mini, Silver or black/red stripe finish
17x7" $249 each, et 40mm, 17.6 lbs each


O.Z. Ultraleggera, black painted finish
17x7" $280 each, et 37mm, 16.0 lbs each

In 18"


Motegi Racing SP10 Hyperblack finish
18x8" $139 each closeout price, et 40mm, 19.0 lbs each

Breyton Race GTS-R Mini, Silver or black finish
18x7" $229 each, et 40mm, 17.0 lbs each

O.Z. Ultraleggera, black painted finish
18x7" $355 each, et 42mm, 17.0 lbs each

About trying to decide on 17" vs 18". If you do choose the Pilot Super Sport, it's such a good tire for street comfort that even with 205/40-18 it's a pretty decent ride that isn't as jarring as it might seem. Not so with other Max Summer tires at any price.

If the Pilot Super sport doesn't sound like a good match for you then if you do decide on 18" wheels then an alternate tire on a budget is-

Sumitomo HTR ZIII Max Summer tire, 300 treadwear
215/35-18 $118 each on special, fits rims 7-8.5" wide, 21 lbs, tire diameter 24" so will fit stock suspension and lowered suspension.
Tirerack test result-
http://www.tirerack.com/tires/tests/...y.jsp?ttid=149
For a budget tire it's pretty well rounded.

For a 17" wheel this same tire comes in 215/45-17 for $83 each, 23 lbs.

 

I'm sold on the Breyton Race GTS-R either in 17" or 18", I'm leaning towards 17" wheels. I keep changing my mind, decisions, decisions, decisions... Can you run lower psi (40) in an 18" wheel to make things softer? Let's say I get the Breyton Race GTS-R in 18"s while keeping the same overall wheel/tire diameter, will I loose a little bit of torque and HP/acceleration?

 

You can try a tire pressure closer to 33 psi instead of 38 psi and see how that works. It's not really needed for the Pilot Super Sport tire in any of the sizes mentioned. Extra high tire pressure would ride firmer though.

By changing wheels and tires you don't loose torque or HP. But if you increase mass you can require more power to do the same work or take longer to do the same work.

Some examples-

Using Breyton Race GTS-R wheels in both examples
17x7 wheel 17.6 lbs
and
Pilot super sport tire in 205/45-17, 20 lbs for total of 37.6 lbs
or
Sumitomo HTR ZIII in 215/45-17, 23 lbs for total of 40.6 lbs

18x7 wheel 17.0 lbs
and
Pilot super sport tire in 205/40-18, 20 lbs for total of 37.0 lbs
or
Sumitomo HTR ZIII in 215/35-18, 21 lbs for total of 38.0 lbs

A difference of 2 lbs per wheel/tire combo is not significant for street use.
I doubt that you can tell much difference based on weight difference alone. The lower sidewall will not flex so it will be very firm if you hit a pothole. It will also be more responsive in handling or turning. Stock suspension will help to cushion the ride.

 

Some background reading before you buy wheels

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

http://grassrootsmotorsports.com/art...ls-of-fortune/

Note that OEM wheels (and budget wheels) are heavy because they need to be strong enough for street use and resist damage from bad roads especially given they often come with runflat tires.
The method of construction, wheel design, etc are all factors for wheel weight.
see
http://www.tirerack.com/wheels/tech/....jsp?techid=90

Forged alloy wheels can be lighter in weight due to the construction process which allows for a stronger but lighter wheel. However as you reduce weight you can reduce the wheel's ability to endure street use. There are some very light race wheels that are not a good choice for daily street driving, nor would you want to risk damaging them due to the cost of replacement.

 

Lightweight wheels make a HUGE difference on the car, only second to changing out the run flat tires for high performance tires.

 

+1
For a daily driver, where you rarely find the MINI's handling limit (IMO), the increase in usability of a 17 or in some cases even a 16 rim DOES have some real advantages.....
Very few MINI's stay on 18's for long...heck MANY GEN1 GP's that came on factory 18's are run on 17's when used as a daily driver.
IMO get the lightest, strongest rims you can afford.
I have always gone for lightness over BLING on getting rims....but I guess rims are to some men what shoes are to my wife!!

 

Budget can be a factor with wheels.

18" light wheels are expensive, 16" relatively light wheels are not that bad on price.

18" wheels require 40 series or smaller sidewalls which can be stiff riding.
17" wheels can use 40 or 45 series sidewalls
16" wheels can use 50 or 55 series sidewalls which can work better for daily use on rough roads.

You don't have to give up good handling by using a tire that is taller on the sidewall if you pick the right tire so shop carefully.

 

I enjoyed my 18" CCW's and I drove on all the good roads and bad roads in SoCal, you'll be fine. I ran 215/35 series tires (Falken 452) and they were fine, never really had any issues and I have to drive through Hollywood streets all the time. My 18s at the time were even lighter than my stock 17s so it wasn't a big issue there either.

Whenever I put on my stocks compared to my forged ltw Volk wheels now though, you can instantly feel the huge disadvantage my mass turning the steering wheel.