AMG Wheels/Tires Larger than Front Wheels/Tires?
12-03-2006, 02:23 PM
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2003 E500 Benz & 2015 BMW M235ix
AMG Wheels/Tires Larger than Front Wheels/Tires?
My current Mercedes alloy wheels that came on my 2003 E500 are the same size on all four wheels: 17x8" and I currently have Pirelli 245/40-17 tires all around (too noisy too). I'm planning on buying new 18" AMG alloys that are 18x8". Is it better to get those same wheels/tires on all four wheels or go with rear wheels that are 18x9" with 265/35-18 tires? The Mercedes catelogue shows most of the AMG 18' alloys with different sized wheels for the front and back. Guess I don't understand why the need for the large sized wheels and tires on the rear of the vehicle: Is it appearance or performance or safety? Some of the Mercedes AMG models, including the E55/E63 models, have the larger sized wheels and tires on the rear although the size looks like rear tires are wider than the front tires but the side wall is smaller size?
12-03-2006, 11:19 PM
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From a design standpoint, when larger tires are used in the rear, the suspension engineer is trying to reduce oversteer and increase understeer. That's what you'll be doing – increasing understeer. This can be undone with camber settings, caster settings, toe, sway bars, spring rates, shocks or bushings.
One thing you may wish to keep in mind, your car has stability control (ESP). That means the ECU knows how fast the wheels are spinning. More importantly, the rotational rate of each wheel. My car has staggered wheels. On my car, the OEM front tires rotate 831 times per mile. The rears rotate 828 times per mile. That's 00.0036% difference. I'm about to go with a brand where if I stayed with the stock sizes, I'd be at 828/813 front to rear. At 00.0184%, that's probably "close enough" with new rubber. However, I go through rears faster than fronts. That means it's possible that I may find myself passing the magic percentage difference that tells ESP something is amiss. By going with the next larger sized rear tire, I'll be at 828/828.
I hope this helps.
One thing you may wish to keep in mind, your car has stability control (ESP). That means the ECU knows how fast the wheels are spinning. More importantly, the rotational rate of each wheel. My car has staggered wheels. On my car, the OEM front tires rotate 831 times per mile. The rears rotate 828 times per mile. That's 00.0036% difference. I'm about to go with a brand where if I stayed with the stock sizes, I'd be at 828/813 front to rear. At 00.0184%, that's probably "close enough" with new rubber. However, I go through rears faster than fronts. That means it's possible that I may find myself passing the magic percentage difference that tells ESP something is amiss. By going with the next larger sized rear tire, I'll be at 828/828.
I hope this helps.
12-04-2006, 06:00 AM
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Interesting points.....thanks. The latest E-Class Sales Booklet indicates for the E550 wheels/tires are 17" 8.0x17 with 245/45R17 tires on all four wheels; Sports Package comes with 18" 8.5x18 front and rear 9.0x18 staggered with tires 245/40R18 and 265/35R18. Also there is a footnote for all the larger wheel/tire options in the booklet: "Lower aspect ratio tires and accompanying wheels provide substantianlly increased treadwear, increased tire noise and reduced ride comfort......" I knew about the harder ride from larger wheels and tires but didn't know there would be more tire noise and faster tread wear from using 18" tires over 17" tires. I plan on moving up from my existing 17" wheels/tires to 18" but now I'm think to get the same sized 18" on all four wheels. Can also better rotate them like my existing 17" sized tires on all four wheels.
12-04-2006, 12:51 PM
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Larger rears (wider) to handle more horsepower in AMG.
I suppose it looks cool too. But if you have to put 460+ hp out to the rear wheels for an E55 (or 490+ for S55), you want a larger contact patch through which to spread the force to the road. You can go with wider wheels/tires in the rear to get that.
I recommend that you stick with 4 matched sizes all around for exactly the reasons you already mentioned. Your choices of brands and loading/speed ratings from the tire industry will be much better, even if you go up a size to 18" and a lower sidewall profile.
I have no options for rotating the tires on my '03 S55. The fronts can't swap with rears, and they are directional performance tires that will not be happy with a swap from side to side.
I recommend that you stick with 4 matched sizes all around for exactly the reasons you already mentioned. Your choices of brands and loading/speed ratings from the tire industry will be much better, even if you go up a size to 18" and a lower sidewall profile.
I have no options for rotating the tires on my '03 S55. The fronts can't swap with rears, and they are directional performance tires that will not be happy with a swap from side to side.
12-04-2006, 11:04 PM
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Yes, my thoughts too about sticking with the same size wheels for all four wheels, whichever new 17" or 18" alloys I decide to buy. I picked up last weekend from my local MB Dealer Parts Dept a free copy of their MB Wheels Booklet that shows all available wheels options for each class vehicle. Too may great choices! I definitely will get either MB wheels from the dealer but better prices on AMG wheels are available from TireRack.com.....can get the Goodyear e F1 GS-D3 summer tires from them too at a very reasonable price already mounted and balanced free with wheels/tires combination purchase.
