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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > Tracking / Racing / Autocrossing > Time for dedicated autox tires! (Questions regarding dif. rim sizes)
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      07-19-2019, 02:44 PM   #1
not good, but bad

Drives: 2013 335i
Join Date: Jun 2016
Location: Bay Area, CA

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Time for dedicated autox tires! (Questions regarding dif. rim sizes)

Hi all,

So I'm really enjoying autox in my F30.

Last week I was tearing it up, snagged 2nd place in B class (1st place was a '18 230i with wheels and suspension work, he beat me by about .4). A few of the other B-class guys were super surprised especially seeing I was on PS4S's. They unanimously said I need to get some RE71's (no point change) on my car and that's where I am now.

My plan is to go square with no other mods (ie camber, suspension, spacers, etc...) Well maybe spacers... 245 all around seems safe. I think I could go up to 255's all around without bumping myself into A class...

My budget is pretty tight (to tight to get new APEX rims) so I'm on the hunt for the least expensive/decent rims I can find.

I have a few questions, I'm finding a lot of OEM staggered setups from F3x's.

For example one BMWCCA facebook member sent me this:
"18x8.5 ET45 and have brand new PS4s 245/35/18
Rears are 18x9.5 ET43 and have 595RSRR 265/40/18
So what happens if I go with different size rims for up front and back, from the very little I know about rims/tires 24(5)5's should still fit but what are the negatives of having different size rims? Does that offset the whole square concept, etc...? How big of a difference are we talking going up to 245/255's up front with RE71's? Any concern losing 10mm on the rear if I go down to 245's?

Thank you very much!
They are spelled BRAKES not breaks!!!! Oh FFS, not another spark plug thread!
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      07-22-2019, 12:06 AM   #2
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Drives: F30 328i Msport
Join Date: Aug 2018
Location: WA

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255's should fit depending on the offset of the wheels.

Currently i'm running 18x8.5 ET30 all around and have a nice flush fitment with a little room to spare for 245's or 255's up front. (currently using 235/45/18's, that size was on super duper liquidation, bought these tires to tear them up )

If you are looking to stay with 18's, I might sell my set of lightweight TRMotorsports C4's (aprox 20-21lbs per wheel).
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      07-22-2019, 08:42 AM   #3

Drives: 428i gran coupe
Join Date: Apr 2015
Location: hawaii

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For decent cheap I suggest konig ampliform, 18x9.5 Et35 with 255/40/18 square.

If you want staggered, Sportline 8s, 18x8.5 ET32 with 245/40/18 front, 18x9.5 ET45 with 255/40(or265/40) rear.
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      07-31-2019, 01:36 PM   #4
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Drives: 2013 335 Sportline with X-dive
Join Date: Jun 2018
Location: Canada

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I autox an F30 335 xdrive (SCCA class is STU). I'm running an 18x9.5 et35 with 265-35-18 RE71s. Plenty of clearance in the rear but i run a 3mm spacer to max track width. I have to run a spacer up front to clear the coilovers. My front fenders are not rolled.

The wheels I'm using are superspeeds RF003RR and they cost less than $1k Canadian so less 32% for US$ purchases or whatever the exchange rate is and you've got yourself a bargain. The RF003 wheels in 18x9.5 format weigh 18.7lbs each which is apex territory.

Here is shot of the car in hard transition...bare in mind that i'm "suspensioned" and hence, lowered about 1.2-1.4 inches in this pic.
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