06-25-2015, 07:54 PM | #1 |
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Question about proper rolling diameter
For 22" wheels:
If I have 265/35 front and 315/30 rear, will that give me the correct ratio for proper rolling diameter front to back? Thanks, jb |
07-01-2015, 01:25 PM | #2 |
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Front outside diameter with the 265/35 is 29.30 inches. Rear outside diameter with 315/30 is 29.44 inches so only a .14 difference. My OEM combination on my 335i has a .18 difference. I think you'll be fine.
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07-01-2015, 02:48 PM | #3 |
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It's unlikely, but you're best bet will be to check the specs for the actual tires you are looking at - 'revs per mile' in particular.
OEM revs per mile are matched exactly...any variation is done at your own peril.
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07-01-2015, 07:41 PM | #4 |
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not completely true, OEM 20' bridgestones are matched exactly, OEM 21' dunlops and michellins all aren't the same. The way a tire sits on the rim, ie stretch and poke will also effect the rolling diameter
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07-01-2015, 09:51 PM | #5 |
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Good call. So that would be your max variance, though personally I'd still prefer an exact match.
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07-02-2015, 02:22 AM | #7 |
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matching and as close as possible would defiantly be good, but i say up to 1% of variance should still be ok, truthfully no one will know until a problem occurs that can be attributed to it.
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07-02-2015, 08:29 AM | #8 | ||
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Quote:
Quote:
IMHO, getting a properly sized set of wheels to go with a properly matched set of tires trumps any savings or 'look' you may get with a wheel brand that doesn't carry X5 specific widths.
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07-02-2015, 02:36 PM | #9 |
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If you look at the original tires
Dueler H/P Sport RFT 275/40R20 315/35R20 Both are 726 revs per mile according to the tirerack The 21' kit I've installed is the same one as MY2015 Michelin PILOT SUPER SPORT 285/35ZR21 721 revs per mile 325/30ZR21 725 revs per mile I don't have any trouble at all and these are BMW approved tires. |
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07-02-2015, 03:01 PM | #10 |
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the 21' dunlops are 723/728. By comparison, 22 pirelli 295/335 should have a much greater variance, pirelli doesn't list the rolling diameter for the front, but the rear is 722, the front is noticeably taller sitting on the ground, my guess would be the front is in the 715 range. Sometime there just isn't much choice as consumers
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