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Discussion Starter #1
I'll mention first that I'm not interested if it makes my car look pretty (you get used to being ugly), this is purely a performance related question...


I'm currently looking at some wheels for trackdays and will be running.

Front: 265/30 ZR19
Rear: 295/30 ZR19

The wheels I'll be getting are:
Front: 9" x 19"
Rear: 10" x 19"

These wheels are therefore both 0.5" wider than stock.

It has been suggested to me that as long as the clearance is ok, I should simply keep the wheels as stock as possible and therefore just add 0.25" to the outside and inside edge of the wheel.

Is this going to be the best solution performance wise? and does anyone know if the clearance is ok on the inside of the tyre? Since installing the H&R springs, I can't get round the back of the tyre checkouich

And

I'm presuming that the wheels are wide enough, but I have come across websites that show the min width of a wheel is 10.5" for a 295 tyre, but I'm pretty sure a 10" wheel will be fine?
 

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My M5 is an e39, but the principles are the same. BMW dialed in a fair amount of understeer in part by using larger tire sizes in the rear and smaller up front. So, rather than keep such similar "stagger" between front and rear sizes, I suggest staying with stock or close to stock rear sizes and upping only the front sizes. Since the M5 is 50/50 weight balanced, the car will handle more neutrally and be closer to ideal with the same sizes all around, though I don't know how much room there is in an e60 up front. I currently run OEM rear wheels on the front of my e39, so that I have 275mm tires all around. This gives the car phenomenal grip and handling, and is a very popular mod with the e39 crowd.

As for how much to add to the inner or outer edges, check out how Dinan modify their cars. Dinan e60 front wheels. It's not as simple as just adding the same to both inner and outer, though that would be ideal for maintaining geometry. You need to clear the shock tubes on the inside and fender lip on the outside edge, so that may dictate more or less inner and outer.
 

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Discussion Starter #3
Understeer is not really an issue on my car, in fact at the moment it has a tendency to oversteer.

I have 2 degrees of negative camber on the front, lowered with H&R and currently H&R adjustable rear sway bar. I still have the stock front anti roll bar but that will change, I now have the Dinan Roll control Kit, but am waiting for the H&R front bar, but if I track it before I get the new H&R front bar, I'll put the Dinan kit on.

I think Handling will then be spot on.

The tyre sizes are very limited in 19's at the moment and getting the tyres I want is the reason for going to 295 and 265. (Toyo R888's)

What I'm suprised at with the Dinan wheels is that they require Wheel Spacers and they also claim to be the lightest 19" x 9" wheel available, "poppy cock..." ;)

My main concern is the clearance between the front tyre and the bottom spring seat on the front strut. I know that people have been running wider wheels and rubber than stock and stock rims with spacers so the outside clearance is fine but it is the inside clearance? especially if I split the extra width of the wheel 50% between outside and inside.
 

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Discussion Starter #4 (Edited)
Been doing some searching.

Looks like I'm going to go with.

Front: 9 x 19 offset 9mm
Rear: 10 x 19 offset 30mm

This I think gives the front outer edge an extra 7.85mm and the inside 4.85mm

On the rear, the outer edge gains an extra 5.35mm and the inside edge an extra 7.35mm

It is possible I have messed up, but I think it is correct this time.

This should then avoid any clearance issues and keep the settings fairly stock.
 
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