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In Reply to: New wheel question...opinions? posted by Stan on June 30, 2000 at 09:53:56:
: There are two schools of thought regarding wheel sizes, 1) keep them all the same size, and 2) wider wheels in the back. Some folks have put the same size all around (say 18x8.5 for example) and others go with wider rears. I've heard two thoughts on #1 - talking with the folks at Dinan, their opinion is that the car is so heavy, that you want the same contact patch all around. The other thought is that it's easier to rotate tires if they're all the same (especially if your running directional tires).
: The obvious thought on having wider rears is putting more power to the ground and maintaining stability through larger contact patch.
: So, I'm soliciting your opinions - same size all around vs. wider in the rear (and please don't quote those stupid car commercials - "Wider is Better".)
: Appreciatively,
: Stan C.
: '92 850iA
I am of a different opinion than some others. Rotation is not as important to me as it seems to be to others. I figured that BMW knew what they were doing when they designed the car, so I went with that. The stock domestic CSi came with 235’s in the front and 275’s in the back, on 17” wheels. BMW never intended for these to be rotated. I currently have 245/40/18 in the front and 285/35/18 in the rear on 18x8.5, on 18x10 wheels respectively. As I understand it, my current tire/wheel combination is the European CSi stock configuration. So again, BMW (BMW Motorsport to be exact) never intended for the tires to be rotated. Besides, the best you can do with a sport tire is swap the fronts with the rears because of the directional nature of the tires. Changing the tires you steer with does not accomplish the goal of an “even ware pattern”. In a staggered configuration the best thing you can do is ensure a proper alignment (I have mine checked once a month (a check does not cost anything, and the alignment labor is covered for 12K miles or 12 months, so it’s just an issue of time)), and I am fanatical about proper tire pressure. You won’t get funny tire ware if you just do those two things.
When I researched my wheels, my goal was to reduce rotating mass. As such, I purchased the lightest wheels I could find for under $3000.00 each, the BBS RC’s. The RC’s are (going off of memory here, so I may be a little off) ~18.75lbs in the 18x10 and 18.25lbs in the 18x8.5. Let’s just say that they are less than 19lbs each, as I know that for sure. The cost is extremely reasonable (less than $500.00 per wheel) because they are cast. I wanted forged, but I could not find a reasonably priced light wheel. The experiment with cast begins (my first set). I chose the Pole Position tires. I considered the Michelin Sports, but they did not come in the exact speed/size combination I wanted, so I stuck to what I knew (I have Pole Positions on my stock CSi wheels, 10K miles and no problems). The Pole Positions are an outstanding tire. I have NO complaints, and I drive my car HARD in turns (as some of you know). I have never seen a bad write-up in any magazine or web site on the Pole Position tires. One thing to note however, you can’t (repeat CAN’T) run the 10mm spacer BBS says you need in the rear with the Pole Positions (works fine with the Michelin's). It will be fine until you start to hot-dog, and then you will have all sorts of problems. The carcass of the Pole Position is the largest of them all. You won’t find a “wider” 285 out there (no difference in tread width, just absolute outside tire measurement). You will have to purchase 5mm spacers from H&R. These work great (Thanks Steve C.!). The car is on rails (and it was not bad before!)
Good luck Stan…looking forward to our next get together!
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