235/40-18 & 255/35-18 on OEM wheels

Artmasterx · 05-02-2009, 11:53 AM

Smaller diameter on the drive tires can help get better acceleration. Up front the smaller sidewall made give a little less "play" in the tires when turning in, but I am not sure if it actually would be noticeable or not (feel or performance wise). If you are worried about rubbing, then I guess smaller is better in that respect as well.

Bdh821 · 05-02-2009, 12:47 PM

^ Thanks for your input. I called tirerack and they recommended I stick with the size I ordered. I'm also gonna do some negative camber by taking out the alignment pin. I just hope I don't have too much "play" feel in my wheel.

oh and artmasterx, sorry I'm terrible with names, but I hope to talk with you more at the next autox

Blue55 · 05-31-2009, 03:53 PM

fourtailpipes did you roll the front fenders to get the 235s on? I just ordered a 135 with the M Sport package and 261M wheels. Do you think I'd be able to get the 235/40-18s on the stock rims without issue? I'll be looking to reduce understeer as much as possible without swapping rims (it's a lease).

jeremyc74 · 05-31-2009, 04:22 PM

Quote:

Originally Posted by Bdh821

So I ordered the same size tires as these, but dunlop direzza star specs. Now I'm second guessing myself and kinda wish i got 235/35/18 up front. Making the speedo read 1.22% faster whereas the 235/40/18 make it read 2.5% slower. I do autocross regularly so I'm thinking the smaller sidewalls would be better? HELP PLEASE!! thanks

Altering the tire size up front won't have any effect at all on the speedo/OD.

Putting larger diameter tires on the rear actually helps correct the error that BMW builds in, but only by a little.

rcracer_tx · 05-31-2009, 04:45 PM

Quote:

Originally Posted by jeremyc74

Altering the tire size up front won't have any effect at all on the speedo/OD.

Putting larger diameter tires on the rear actually helps correct the error that BMW builds in, but only by a little.

Jeremy, the computer knows exactly how fast you are going, but purposely shows a speed lower... You can see this by looking at the diagnostics via a BT scanner. Their is an actual speed and a shown speed on speedometer when looking through the options for datalogging. they are not the same

05-02-2009, 11:53 AM	#23
Artmasterx Captain 46 Rep 884 Posts Drives: 2007 BMW 335i Join Date: Jun 2008 Location: MA iTrader: (0) Garage List 2006 Volvo V70R [10.00] 2007 BMW 335i [10.00]	Smaller diameter on the drive tires can help get better acceleration. Up front the smaller sidewall made give a little less "play" in the tires when turning in, but I am not sure if it actually would be noticeable or not (feel or performance wise). If you are worried about rubbing, then I guess smaller is better in that respect as well. __________________ Current: 2007 335i sedan Alpine White \| Sports \| Premium \| Cold \| Comfort Access FORMERLY: 128i coupe Alpine White \| Sports Package \| Black Leather
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05-02-2009, 12:47 PM	#24
Bdh821 Major 44 Rep 1,265 Posts Drives: 2021 M550i Join Date: Feb 2008 Location: MA iTrader: (3)	^ Thanks for your input. I called tirerack and they recommended I stick with the size I ordered. I'm also gonna do some negative camber by taking out the alignment pin. I just hope I don't have too much "play" feel in my wheel. oh and artmasterx, sorry I'm terrible with names, but I hope to talk with you more at the next autox
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05-31-2009, 03:53 PM	#25
Blue55 Lieutenant 69 Rep 420 Posts Drives: 1M Join Date: May 2009 Location: Earth iTrader: (0)	fourtailpipes did you roll the front fenders to get the 235s on? I just ordered a 135 with the M Sport package and 261M wheels. Do you think I'd be able to get the 235/40-18s on the stock rims without issue? I'll be looking to reduce understeer as much as possible without swapping rims (it's a lease).
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