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01-08-2008, 08:14 AM | #1 | |
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fourwheel drive models
Hi,
Could anyone explain why all wheels bigger than 18" x 8.5" is rated as not suitable for X models? Everywhere you look it says something like Quote:
And on the other side you have people running bigger rims without any problems, like rldzhao on http://e90post.com/forums/showthread.php?t=100153 (Btw, Thanks for your support over PM ) I will get my 2008 335iX week 7 and this is confusing. Anyone care to take a guess? |
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01-08-2008, 08:49 AM | #2 |
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Because BMW doesn't recommend a staggered setup for the Xi models?
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01-08-2008, 09:17 AM | #3 |
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But they ship style 194M with my car (sport package) i.e. 17x8 front, 17x8.5 rear ......
Could you explain what "staggered setup" means? |
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01-08-2008, 09:30 AM | #4 |
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In Canada they ship the 18" style 162 staggered on the xi cars as part of the sport package.
The tires are the summer RFTs. No problem with staggered but the dia of the tires for front and rear must be closely matched to prevent f'in up the AWD. You really gotta be careful to make sure they are very close. Last edited by sparkyg; 01-08-2008 at 09:30 AM.. Reason: added details |
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01-08-2008, 10:08 AM | #5 | |
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Quote:
As sparkyg said, the tire diameter must be well matched in order for the X-drive to hold up. With a staggered setup it's very hard, if not impossible, to achieve the same diameter for front and rear. But as that doesnt seem to be a problem I'm out of ideas...
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01-08-2008, 10:25 AM | #6 |
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I always thought "staggered" meant larger diameter wheels in the rear (i.e. 18" Front / 19" rear), not varying width (i.e. 8" and 8.5")
Typically, different wheel diameter on an AWD car (front to back) is a big no-no for your differentials, because they will be constantly acting to correct the different load, grip, etc. Some car manufacturers of AWD cars even suggest not putting rubber of substantially different tread wear on different corners, as the grip will be different enough to effect differentials. |
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01-08-2008, 10:43 AM | #7 |
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Ah... I think I understand.
So for exampel, using 19 x 8.5 front (235/35) and 9.5 rear (275/30) == 0.02 in. difference (0.077%) is better than using 19 x 8.5 front (235/35) and 9.5 rear (265/30) == 0.217 in. difference (0.857%) Thanks for the replys |
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01-08-2008, 12:03 PM | #9 |
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The diff is less than that of what I will have my factory staggered 18's so I say no problem.
The factory 18" setup has a -0.236% diff. I would contact Gary@Tirerack to confirm. They know their sh*t and have dealt with the xi cars for longer that we have. The 19" setup of 235/35 and 275/30 is the best since it is almost exact. That is the way I am going. Also, check w/Gary on the tires your choose. Some tires are weird and their dia. on paper do not relate to the real world diam. I am not sure why, manufatcturing or if this is due to design. I know the Michelin PS2 will work great. |
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01-08-2008, 03:08 PM | #11 | |
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Quote:
They stagger the front to rear widths from 8" to 9". If this % variation analysis holds water, I'd say you should be fine. |
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01-08-2008, 03:32 PM | #12 |
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I dont really see the point of staggered on Xi models. Sure it may look nice, but for handling purposes i would think it would be best to just go with a 235/245 all around.
The main reason alot of people here go 265+ in the rear is to help get the power down, our xi's don't have that issue. And doesnt staggered setups induce greater amounts of understeer. Correct me if im wrong, my understanding of suspension setups are basic at best. |
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01-08-2008, 03:54 PM | #13 |
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In the swedish pricelist all rims bigger than 18" is marked with "not for fourwheeldrive models"
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01-08-2008, 03:55 PM | #14 | |
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Quote:
That makes sense..... |
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01-08-2008, 04:03 PM | #15 | |
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But in terms of handling I am not sure if a rear staggered design induces more understeer. All rear drive high end sports cars stagger their set up. From front engine mount to mid mount so I know a front wheel drive car has constant understeer problems but in terms or a rear wheel biased AWD there will be more understeer than its pure rear drive equivalent but for performance sake you may need to drive the AWD diff. than the rear wheel drive. Prob need to get on the gas more through the corner than say a RWD. |
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01-08-2008, 05:50 PM | #16 |
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alright I didn't read all the posts because they seemed to long and boring but I'm running a staggered setup on my XI and have notice a difference, we've been having a lot of rain lately and I actually notice more grip now.
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01-08-2008, 05:57 PM | #17 | |
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The xi is rear biased, so the wider rears are still applying better traction to the wheels with more power. The "stagger" isn't really that severe, so I don't think it'll have a very drastic effect on under/oversteer. |
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01-08-2008, 05:59 PM | #18 | |
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01-09-2008, 06:46 PM | #20 |
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I'm glad someone brought this up cuz I too am awaiting delivery of my '08 335xi and will undoubtedly put new wheels on it. From a practicality and safety standpoint I'm almost inclined to just run a 19x8.5's with 235's all the way around. Def save some dough on tires (at least as far as the rear is concerned) and can still rotate the tires.
The bad side wants the staggered setup since it just looks so nice. Let's be honest here, is there really a significant difference in performance while running staggered? Or are we talking something like another .02 lateral g's and maybe a .05 sec's faster 0-60? Cuz realistically, I'm never gonna really FEEL the difference, nor will I be in such a tight competition that I'd actually need it. Ya know? Thomas, any word from Gary@TireRack? |
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01-09-2008, 09:34 PM | #21 |
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[QUOTE=NoSole;1935451]I'm glad someone brought this up cuz I too am awaiting delivery of my '08 335xi and will undoubtedly put new wheels on it. From a practicality and safety standpoint I'm almost inclined to just run a 19x8.5's with 235's all the way around. Def save some dough on tires (at least as far as the rear is concerned) and can still rotate the tires.
2 obvious advantages The bad side wants the staggered setup since it just looks so nice. True, but if the wheels do not have lips, is the "staggered look" even evident? |
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