Quote:
Originally Posted by DallasDave X5M
I am looking for all season tires for our X5 M with 21" wheels. There seems to be NOTHING in the OEM size.
What do you guys think if I went with 275/35-21 in the front (instead of the 285/35-21) and 315/30-21 (instead of the 325/30/-21)? The overall tire diameters are close.
OEM size front is 28.9" in diameter and the alternate size is 28.7" (about 5mm difference in DIAMETER, so the radius would be like a nickel thick)
OEM size rear is 28.7" in diameter and the alternate size is 28.4" (not quite 8mm difference in DIAMETER, so the radius would be like two nickels thick)
The alternate sized tires would be Michelin Pilot Sport A/S 3+
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I think you should be fine. The front/rear rotational diameter difference is 0.7% in OEM 21", which is also preserved in your combo. The change in Speedo difference due to different diameters from OEM is trivial (about 0.9 mph at 90 mph). The 315/30/21 from MP AS 3+ seems to be a newer release, and quite surprising that Michelin is continuing to invest in a "deprecated" model. I might consider this seriously as well.