Luke: wheel & tire upgrade questions...

Luke, I currently own a 1994 BMW 740i. When I purchased it, it had aftermarket tires and wheels on it. I believe the stock rim diameter for this model year was a 15" wheel. The wheel size on it is now 18". The wheel brand is "Atech" or "Alloy Technologies". There are no apparent markings on the wheels to indicate model or width, but after doing sonme online and local merchant inquires, I believe them to be a model 629, which come in an 18" in an 8" width only (not 18x8.5, as near as I can tell). The tires on them are Kumho Ecsta Supra 93W size 245 40ZR/18. I have read about wheels needing the proper fitment, mentioning offset and centerbore and boltpattern. It seems that these wheels/tires may be causing an ever-so-slight rub against the top of the struts on the front end, due to width and/or offset. I am concerned that the previoius owner may have chosen the wrong wheel/tire combo for the upgrades. I like the 18" wheel size, but I want to be reassured of the correct size as not to make the speedo/odometer be inaccurate, and to have no rub. I want all 4 wheels the same WIDTH so I can rotate front to back for maximum tire mileage and minimum wear. If I stay with an 18" tire what is the correct tire size/ is my current tire size accurate? If I stay with an 18" wheel, what is the correct centerbore/offset/fitment, and is 8" wide ok? Until I can purchase new wheels, can I use spacers with my current wheels, and do I need longer lugnuts if I use spacers?
thanks!
-Chris

here's my take .... if I don't miss with my guess I would say that your wheel is an 18x8 with a 35mm offset (this is a very common size/offset) however your car requires a lower offset. The higher offset would cause rubbing on the inside of the wheel against the suspension components. Your car should be using a 20mm offset on an 18x8 wheel. The tire size of 245/40-18 is correct

Luke, Thank you for the reply to this thread, as well as the time you spent on the phone with me. Grab a cup of Coffee before you read on, it's a long post! I took my wheels to the local tire shop, and they measured them at 8.5" wide (can you say rub??). Glad there was only less than 1K on this set of tires before I realized the last owners wheel offset goof, the tires and rims were new when I took delivery of the car. No damage to car, wheels or tires due to the very minimal rub. I am definitely purchasing new wheels (and tires too). I originally thought about the Inspirations, and you pointed me towards the Visions. After thinking about it, I am actually swaying a bit more towards the Magics. whaddaya think?? I think I want a bit more conservative look. I also am going to downsize to a 17" wheel, giving me more choices on for tires, now and for replacing in the future, also a little smoother ride, not to mention a little bit in $$ savings when comparing 17" wheels and tires to 18" wheels and tires. I'll buy 17" same size front and rear so I can rotate for maximum wear. Your tire size selector recommends 235/45 17". I have a good friend who used to be in the tire business, I am using a bit of his knowledge base to help my decision, he has never steered me wrong in the past (no pun intended). I have never been a big fan of Goodyear, Dunlop, Goodrich, Conti, Michelin or Pirelli. I think people pay for the name, and that's it. My ego doesn't need the "Bling Bling" factor (and cost) for these tires. I have personally had horrible luck with Pirelli (sidewall splitting AND poor mileage), and also poor luck with Michelin (ride, noise, and again, poor mileage). A big concern is blistering/bulging sidewalls which I have seen on some expensive tires. I have personally have had great success with Bridgestone (Potenza) and Firestone (Firehawk) tires in the past. I think they are well kept secrets in the tire world. Firestones also don't scare me as I don't own a Ford Ex-"PLODE"-r. I have narrowed down to Bridgestone (re950, re750, re730 gen2, s3 pole position), firestone SZ50 EP, Yoko AVS DBs2, and the Kumho supra 712 and exta mx, and am reading the reviews for the benefits and tradeoffs. I know, very different tires across the board, BUT I'm swaying to my top 3 of the 8: the SZ50EP, the 730 GEN 2, and the Kumho 712. I am curious about any advanced feedback you may have on the new RE750's, and any input you have on the Yokos. The Kumho's are intriguing because of the bang for the buck factor, and I have Kumhos now. They seem to rate well, even for their price. The Kumhos seem to be the "little-tire-that could", compared to the more famous brands. In the long haul, For around $100 each in the 17" size, I can buy 3 sets for less than 2 sets of competitors brands that seem to have equal or lower mileage and performance ratings. Or if I trash one the replacement cost is cheap. And, I could use the extra savings to help buy an extra set of blizzaks for a pure winter performance tire. I think people that post reviews on the board tend to have higher expectations, and are then let down or unrealistic about the performance of the more expensive tires, while being more than satisfied, having their expectations exceeded, with lesser expensive kumhos (or other lesser known/priced brands). Seems the reviews tend to have a direct correlation to the price in some cases. I also get a kick out of the people who even remotely think they could pass off using these ultra high performance tires in the snow with any expectations of traction, but I'll reserve any more comments on that for another thread altogether. I just can't justify shelling out 150+ per tire (up to near 300 for some models) on ANY tire if they are going to wear out quickly, or if the quality is overrated versus actual performance versus the price. Read this post and digest it when you get a chance. If it's easier, just send a reply rather than a long post and I'll give you a call. I will be purchasing probably around tax day or just thereafter, and I'd assume give you the credit for the sale rather than one of your co-workers for the help you've been so far. I'd also like to know where I could post my current tires and wheels that are pictured on the car in the photo for sale; you did mention something about posting them in some forum someplace when I talked with you on the phone last week. They are Alloy Technologies (A-TECH) model 629 Chrome wheels, 18x 8 (or 8.5), with Kumho Ecsta Supra 245/40ZR18 tires.
-Chris

although a long post it is very easy to understnad what you are looing for and the tires that you have narrowed your search down to are a good group .... but, the hands down winner would be the Firehawk SZ50's and the competition isn't that close ..... I am actually putting a set of those on my own car next week .... The Breyton Magic wheel is very nice but somewhat harder to clean than the Visions .... As far as where to dump your chromies post them on EBAY ....

Thanks again Luke.
With respect to the wheels Problem:
I like the look of the visions and agree with you about the easy-to-clean situation. HOWEVER, they look chrome or painted silver. What is the finish like?
I like the Magics, and agree with you about the not-so-easy-to-clean situation. Are they more of a brushed aluminum finish? Breyton's website makes both wheels look fake, and I looked on ebay for some good pictures without much luck, as the ones pictured on actual cars on ebay were 19s.
The tirerack shows them as more of an animation than as an actual wheel. Any idea where I could get good closeup shots of both wheels? One of each straght-on, and one of each at an angle?
If the Visions are silver or chrome, then I think those are OUT, as they look too much like the bling-bling chromies i have now. If they are a matte or brushed finish, then I will likely go with them over the Magics.
I don't wnat to open the box and have the wheels be chrome, or like they just got painted with silver Krylon.
If you could point me to some photos I'd appreciate it!
-Chris
P.S.... the SZ50's were my secret 1st choice!

the finishes on both wheels is very nice ... the Magic has a silver painted center section and a machined lip area .... the vision has a brilliant silver painted finish ... neither wheel looks "Krylon esque"