how can i optimize handling with bigger wheels/tires (17x7 - 205/45r/17)?
#1
08-05-2010 | 01:35 PM
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3rd Gear
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From: SoCal
how can i optimize handling with bigger wheels/tires (17x7 - 205/45r/17)?
i have a base '07 r56 cooper
just put 1000 miles riding on my new enkei rpf1's w/hankook ventus v12 evo's
going from stock 15x5.5 - 175/65r/17 to these have changed handling considerably
how can i make the most of my new wheels and tires to get the most grip?
i have only 3 suspension mods (rear sway bar, strut brace & x-brace)
i know the jcw comes stock w/the same size wheels and tires, what exactly are the differences in suspension between the jcw and base cooper?
thanks!
just put 1000 miles riding on my new enkei rpf1's w/hankook ventus v12 evo's
going from stock 15x5.5 - 175/65r/17 to these have changed handling considerably
how can i make the most of my new wheels and tires to get the most grip?
i have only 3 suspension mods (rear sway bar, strut brace & x-brace)
i know the jcw comes stock w/the same size wheels and tires, what exactly are the differences in suspension between the jcw and base cooper?
thanks!
#4
08-06-2010 | 09:33 AM
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3rd Gear
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From: SoCal
richardsperry - thanks but that doesn't help me, i wasn't asking how i can drive better/faster.
the problem is that with my new wider wheels/tires the car has actually lost grip despite the tires being max performance summers.
the tires are definitely scrubbed in after 1000 miles but they lose grip sooner than my stock ones did.
thats why i want to know what suspension settings/parts are for the jcw which comes stock w/17x7's
-slinger688
my rear bar is an h-sport 25mm hollow at full stiff. camber settings are stock in the rear (i believe -1 degrees?)
the problem is that with my new wider wheels/tires the car has actually lost grip despite the tires being max performance summers.
the tires are definitely scrubbed in after 1000 miles but they lose grip sooner than my stock ones did.
thats why i want to know what suspension settings/parts are for the jcw which comes stock w/17x7's
-slinger688
my rear bar is an h-sport 25mm hollow at full stiff. camber settings are stock in the rear (i believe -1 degrees?)
#6
08-06-2010 | 10:10 PM
the problem is that with my new wider wheels/tires the car has actually lost grip despite the tires being max performance summers.
the tires are definitely scrubbed in after 1000 miles but they lose grip sooner than my stock ones did.
thats why i want to know what suspension settings/parts are for the jcw which comes stock w/17x7's
-slinger688
my rear bar is an h-sport 25mm hollow at full stiff. camber settings are stock in the rear (i believe -1 degrees?)
I believe the h-sport 25 mm hollow is equivalent to a 22 mm solid. That is a very aggressive bar set at a very aggressive setting. Just wanted to let you know that more sway bar is not necessary better handling!
#7
08-06-2010 | 10:21 PM
Back of the rear bar to full soft and start there.
Get some front camber plates to better use the rubber at the front end.
When you mean you loose traction, is it on all surfaces, or just on rough/poor surfaces?
I'm guessing that you have too much rear bar for what the rest of the suspension is doing, and it's going loose in the rear much earlier than the factory understeer was plowing, resulting in lower overall cornering levels. Anyway, you're not running an extreme tire/wheel combination, so you get the rest of the stuff set up to take advantage of the new rubber, and you'll be turning circles around what the car used to be able to do.
Matt
When you mean you loose traction, is it on all surfaces, or just on rough/poor surfaces?
I'm guessing that you have too much rear bar for what the rest of the suspension is doing, and it's going loose in the rear much earlier than the factory understeer was plowing, resulting in lower overall cornering levels. Anyway, you're not running an extreme tire/wheel combination, so you get the rest of the stuff set up to take advantage of the new rubber, and you'll be turning circles around what the car used to be able to do.
Matt
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#8
08-07-2010 | 07:57 AM
Get some front camber plates to better use the rubber at the front end.
When you mean you loose traction, is it on all surfaces, or just on rough/poor surfaces?
I'm guessing that you have too much rear bar for what the rest of the suspension is doing, and it's going loose in the rear much earlier than the factory understeer was plowing, resulting in lower overall cornering levels. Anyway, you're not running an extreme tire/wheel combination, so you get the rest of the stuff set up to take advantage of the new rubber, and you'll be turning circles around what the car used to be able to do.
Matt
When you mean you loose traction, is it on all surfaces, or just on rough/poor surfaces?
I'm guessing that you have too much rear bar for what the rest of the suspension is doing, and it's going loose in the rear much earlier than the factory understeer was plowing, resulting in lower overall cornering levels. Anyway, you're not running an extreme tire/wheel combination, so you get the rest of the stuff set up to take advantage of the new rubber, and you'll be turning circles around what the car used to be able to do.
Matt
#10
08-07-2010 | 10:14 AM
#11
08-07-2010 | 03:16 PM
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3rd Gear
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From: SoCal
#12
08-07-2010 | 05:06 PM
Don't take the the wrong way...
but just bolting crap onto the car is a sure way to loose handling. Suspension tuning is part art, part science, and part magic.
In general, the factory difficiencies on the stock suspension are a lack of front camber made worse by the fact that there is little camber gain with suspension compression. You get some induced camber by turning via the factory caster setting. But not tons. net result of this is that the front contact patch isn't optimized for agressive turning. Correcting this will improve front end traction, decrease (but usually no eliminate) understeer.
The second difficiency is that the car comes with understeer from the factory. This is for the safety of the masses, because most drivers can deal with plow better than the rear end sliding first and the car spinning. Plow or push also scrubs off speed pretty quickly.
IF all your suspension is stock but the rear bar, and you have the bar you have on full stiff, you may think that you're braking loose at both ends at the same time, but it's not likely. Another thing that will happen with this set up is that you are turning, lift off the gas, and the rear end gets very, very loose very very quickly.
A very good place to start for improved handling on the stock car, is some camber plates (fixed ones are fine unless you are going to go to the track a lot, and you a very good driver) and a mild upgrade to the rear bar. What you've described is a huge increase in rear bar stiffness. While some may like this, it's not a good place for those that are learning performance driving to start on our cars.
You really have a couple of choices. First thing to do is to play with tire pressures a lot. You don't mention what you're running now, but going to lower pressures softens up the tire. doing different things to front/rear tire pressures will change the front/rear traction bias as well. If it were my car I'd back the rear bar off to full soft (I think that is still stiffer than stock). Play with this a lot.
Next thing I'd do is get a good book and read it. Puhn's "how to make your car handle" is a standard reference, but there are many good ones.
Next, even after you read this, is to find a really good suspension/allignment shop close to you and work with them. The one I use has guys that tell me what's wrong with my driving, pressures and lots of other stuff by reading my tread wear, then we talk about suspension changes that will improve what I want from the car coupled to how I actually drive it.
Long and short, the answer to your questions are probably yes, but there are a lot of other things that go into the mix that means it's not a definint yes.
Hope all this helps....
Matt
In general, the factory difficiencies on the stock suspension are a lack of front camber made worse by the fact that there is little camber gain with suspension compression. You get some induced camber by turning via the factory caster setting. But not tons. net result of this is that the front contact patch isn't optimized for agressive turning. Correcting this will improve front end traction, decrease (but usually no eliminate) understeer.
The second difficiency is that the car comes with understeer from the factory. This is for the safety of the masses, because most drivers can deal with plow better than the rear end sliding first and the car spinning. Plow or push also scrubs off speed pretty quickly.
IF all your suspension is stock but the rear bar, and you have the bar you have on full stiff, you may think that you're braking loose at both ends at the same time, but it's not likely. Another thing that will happen with this set up is that you are turning, lift off the gas, and the rear end gets very, very loose very very quickly.
A very good place to start for improved handling on the stock car, is some camber plates (fixed ones are fine unless you are going to go to the track a lot, and you a very good driver) and a mild upgrade to the rear bar. What you've described is a huge increase in rear bar stiffness. While some may like this, it's not a good place for those that are learning performance driving to start on our cars.
You really have a couple of choices. First thing to do is to play with tire pressures a lot. You don't mention what you're running now, but going to lower pressures softens up the tire. doing different things to front/rear tire pressures will change the front/rear traction bias as well. If it were my car I'd back the rear bar off to full soft (I think that is still stiffer than stock). Play with this a lot.
Next thing I'd do is get a good book and read it. Puhn's "how to make your car handle" is a standard reference, but there are many good ones.
Next, even after you read this, is to find a really good suspension/allignment shop close to you and work with them. The one I use has guys that tell me what's wrong with my driving, pressures and lots of other stuff by reading my tread wear, then we talk about suspension changes that will improve what I want from the car coupled to how I actually drive it.
Long and short, the answer to your questions are probably yes, but there are a lot of other things that go into the mix that means it's not a definint yes.
Hope all this helps....
Matt
#14
08-08-2010 | 09:56 AM
#15
08-08-2010 | 01:30 PM
Just so you know the factory JCW does not have any different suspension than a base Cooper. It has the same base and sport suspension options, as well as the JCW suspension available. I have the base suspension as the roads where I live are horrible, especially in winter, so I'm sticking with comfort for now while I weigh all my suspension options. So there's nothing wrong with your stock suspension when it comes to working with 17x7 and 205/45/17s.
#16
08-08-2010 | 02:00 PM
From my perspective " how can i optimize handling with bigger wheels/tires" could be an oxymoron -- Should the bigger tire/wheel combination be heavier than the original.
On my cooper I ran out and got a bigger tires/wheels and quickly discovered that I had hurt performance and handling. The larger diameter gave me even higher gearing and the big heavy tires really hurt handling.
I have since switched to smaller (205/50/15) and lighter wheels/tires and it has made a big improvement. The smaller diameter tires improved the gearing dramatically and the cutting about 7lbs a corner un-sprung weight makes the MINI handle much better especially on rough surfaces.
On my cooper I ran out and got a bigger tires/wheels and quickly discovered that I had hurt performance and handling. The larger diameter gave me even higher gearing and the big heavy tires really hurt handling.
I have since switched to smaller (205/50/15) and lighter wheels/tires and it has made a big improvement. The smaller diameter tires improved the gearing dramatically and the cutting about 7lbs a corner un-sprung weight makes the MINI handle much better especially on rough surfaces.
#19
08-09-2010 | 09:57 AM
Wow I've really learned a lot from this post! Also I'm realizing that I don't know as much as I think I know about all of my handling bolt-ons...
I just installed Bilstein PSS9s on my '03 R53 (ordered from Tire Rack) with helix adj front camber plates, H-sport lower rear control arms, and the H-sport 22.5mm adj rear sway bar set on the middle setting.
I have -1.6 degrees camber dialed up front and about -1.3 on the rear. Running 215/45/17 Hankook Ventus V12 Evos.
I'm really considering going to a 16" wheel, or even 15" if it will clear my R53 JCW brakes.
I'm assuming this will benefit me as well?
I just installed Bilstein PSS9s on my '03 R53 (ordered from Tire Rack) with helix adj front camber plates, H-sport lower rear control arms, and the H-sport 22.5mm adj rear sway bar set on the middle setting.
I have -1.6 degrees camber dialed up front and about -1.3 on the rear. Running 215/45/17 Hankook Ventus V12 Evos.
I'm really considering going to a 16" wheel, or even 15" if it will clear my R53 JCW brakes.
I'm assuming this will benefit me as well?
#22
08-09-2010 | 01:18 PM
#23
08-09-2010 | 03:46 PM
But there is the trade off of brake size -- the advantage of the 17 is you can fit larger brakes under them.
As stated my preference is light weight 15 inch wheels and tires
This is an interesting parallel thread:
https://www.northamericanmotoring.co...o-you-run.html
#25
08-09-2010 | 06:49 PM
Many Porsches at the track exchange their heavy 19" for the lighter 18" rims. They can get just as wide tires for their 18" rims.