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#1
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My 97 528 in riding on tires sized 225/55/R16 tires. The inside of my
wheels are stamped 7Kx16. The manual states that the tire specification for this is exactly what is on the wheels; 225/55/R16. When I research tires I find that there seem to many more 225/60/16 tires available than 225/55/16. A local BMW mechanic is adamant that 225/60/16 are what is supposed to be on this car. I suppose the wheels could have been swapped, however they are BMW wheels and seem to be about the correct age ( base on what I think the wear should be ). This wheel is aluminum and has 20 ribs in it. What do you think? Was this wheel common on a 97 528? Could my car originally have come with tires sized 225/60? |
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#2
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The tire sidewall can be calculated by multiplying the width (225) by the
aspect ratio (.55 or .60). The difference is about 13 mm, or 1/2 inch in the sidewall, or about 1 inch across the diameter. This is significant. The door post should have a sticker that tells you what the tire options were. My car (a '94 3 Series) came with the sports package that included 225/55x15. It turns out that this tire size is now very rare, and replacements come at a price premium. I went on eBay and found a set of 17" rims from a '95 M3, and the tires are now 225/45x17. The overall tire diameter is within one-quarter inch of the stock size, so I am in good shape. I think that your choices as factory fitment are going to be the 225/55 or 205/60, but not 225/60. The difference in the 225/55 and the 205/60 is less than 1.5 mm on the diameter. 225 x .55 = 123.75 mm, 205 x .60 = 123 mm. 0.75 mm on the radius (or sidewall) is 1.5mm on the overall diameter. If you went to a 17" rim and kept the 225 tire width, then you would want to buy a 225/50x17 to have essentially the same size tire overall. A 225/55x16 is an overall diameter of 26 inches. 225 * .55 = 123.75, or 5 inches. This is one sidewall. The rim is 16, so the rim plus the sidewall on each side will give you the overall diameter of 26 inches. Using the same formula for a 225/50x17 gives us a sidewall of 112.5 mm, or 4.5 inches. 17 + 9 = 26, so the overall diameter of a 225/55x16 is equivelent to a 225/50x17. If there was a significant difference in the price of the tires, the cost of the new rims could easily be recovered by the time you purchase the second set of new tires. You can see the wheel options here, http://www.wattora.com/Mods/OBDII/, and you can find rims on eBay if you search for BMW OEM 17" WHEELS, you might have better luck if you include your model, E39 or whatever your car is. My car is an E36, so I searched for BMW OEM E36 17" WHEELS. This search excluded aftermarket rims and rims for the 5 and 7 Series. You could also consider a 235/50x17, or a 235/45x17. The /50 would give you a half inch taller tire and the /45 would give you a half inch shorter tire. The difference in diameter calculates into the circumference, and by extension into the final drive ratio. I would go with the slightly smaller diameter if I was faced with the choice, but a half inch in diameter is nothing in the grand scheme of things. You could also work the calculations for 18" wheel options. "Stan Dowiat" > wrote in message ... > My 97 528 in riding on tires sized 225/55/R16 tires. The inside of my > wheels are stamped 7Kx16. The manual states that the tire specification for > this is exactly what is on the wheels; 225/55/R16. > > When I research tires I find that there seem to many more 225/60/16 tires > available than 225/55/16. A local BMW mechanic is adamant that 225/60/16 > are what is supposed to be on this car. > > I suppose the wheels could have been swapped, however they are BMW wheels > and seem to be about the correct age ( base on what I think the wear should > be ). This wheel is aluminum and has 20 ribs in it. > > What do you think? Was this wheel common on a 97 528? Could my car > originally have come with tires sized 225/60? > > |
#3
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The mechanic is wrong - he is mistakenly thinking of 15-inch rims. The
standard tire size for 15-inch rims on a '97 528i is 225/60-15. For 16-inch rims, as you've already noted, the correct size is 255/55-16. If you use 225/60-16 tires on your 528i your speedometer will no longer be as "accurate" as it "should be". It will show a slower speed than otherwise intended by BMW. You may more readily get a speeding ticket and your on-board computer may go out of whack. 225/60-16 size tires may be more common but they are likely of lower performance characteristics. Many are probably grand touring tires. 16-inch rims are actually of a commonplace rim size but BMW chose the 225/55-16 tire size for performance reasons so that is why there are more tires available at a 60 aspect ratio vs a 55 aspect ratio. Remember that the standard rim size for a '97 528 was 15-inch. By definition, the tires on the 16-inch rim for the 528i is for performance and will be more rare on the road. |
#4
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Given that the E39 typically has a significantly optimistic speedometer,
going to 60 series would likely eliminate most of the error. Of course, if you're accustomed to travelling @ 83 indicated in a 70 zone (75 indicated + "8 over" for an actual 78 mph ... will often slip under law enforcement radar), you're probably going to attract some attention. The 60 series tire might right a bit better, corner a bit worse. R / John "Michael Low" > wrote in message oups.com... > The mechanic is wrong - he is mistakenly thinking of 15-inch rims. The > standard tire size for 15-inch rims on a '97 528i is 225/60-15. > > For 16-inch rims, as you've already noted, the correct size is > 255/55-16. > > If you use 225/60-16 tires on your 528i your speedometer will no longer > be as "accurate" as it "should be". It will show a slower speed than > otherwise intended by BMW. You may more readily get a speeding ticket > and your on-board computer may go out of whack. > > 225/60-16 size tires may be more common but they are likely of lower > performance characteristics. Many are probably grand touring tires. > > 16-inch rims are actually of a commonplace rim size but BMW chose the > 225/55-16 tire size for performance reasons so that is why there are > more tires available at a 60 aspect ratio vs a 55 aspect ratio. > > Remember that the standard rim size for a '97 528 was 15-inch. By > definition, the tires on the 16-inch rim for the 528i is for > performance and will be more rare on the road. > |
#5
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![]() "Jeff Strickland" > wrote in message ... > The tire sidewall can be calculated by multiplying the width (225) > by the > aspect ratio (.55 or .60). > <snippety snip> All of what Jeff said is true, except you must also consider that some (many) manufacturers vary their measurements and ratings a bit. Anyway, you can get the real (measured) tire circumferences off of the tirerack web site for any tire you are considering and then compare it to the stock tires to determine how much actual difference ther will be. http://www.tirerack.com/index.jsp By the way, it appears there is no shortage of the correct sized tires there on their web site. A larger diameter tire and the resulting taller gear ratio (smaller number:1) may not be a bad thing if you are primarily a freeway driver. OTOH you may want to go with a smaller diameter wheel for a shorter overall drive ratio if you are more interested in acceleration performance. -Fred W |
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