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

fourtailpipes · 04-18-2009, 09:14 AM

mounted my re01r 235/40-18 & 255/35-18 on stock staggered wheels. no rubbing. excuse the dirty wheels.

C4747Z · 04-18-2009, 09:18 AM

How does the car drive? what kind of tires did you put on the car?

ptack · 04-18-2009, 12:41 PM

Nice that they fit, but they seem to look a little balloonee.

fourtailpipes · 04-18-2009, 06:25 PM

they're bridgestone potenza re01r 235/40-18 and 255/35-18. they're for go, not show, and i suspect that i could have done 245 up front without issue.

ssabripo · 04-18-2009, 06:37 PM

can you take some cleaner and close up pics of the rears? thanks in advance.

gonna be mounting mine next week, but running 10mm spacers in the rear, so I suspect some rubbing to occur.

1013mm · 04-18-2009, 06:48 PM

Quote:

Originally Posted by ptack

Nice that they fit, but they seem to look a little balloonee.

.

fourtailpipes · 04-18-2009, 07:08 PM

Quote:

Originally Posted by ssabripo

can you take some cleaner and close up pics of the rears? thanks in advance.

gonna be mounting mine next week, but running 10mm spacers in the rear, so I suspect some rubbing to occur.

i'll try to get some more tomorrow... if you're on stock wheels, i doubt it'll work with 10mm spacers, unless you're playing with your rear camber (which in my opinion isn't worth it).

ssabripo · 04-18-2009, 08:02 PM

Quote:

Originally Posted by fourtailpipes

i'll try to get some more tomorrow... if you're on stock wheels, i doubt it'll work with 10mm spacers, unless you're playing with your rear camber (which in my opinion isn't worth it).

no, i'm not playing with camber, but I'm willing to fender roll.....anyways, lets see how the pics look

fourtailpipes · 04-18-2009, 08:56 PM

the 2nd picture shows the rear pretty closely... even with more fender rolling, i seriously doubt there's 10mm to play with.

lib · 04-18-2009, 10:14 PM

Hmmm....

I was about to buy a set of Direzza Star Specs in 225/40-18 & 255/35-18 but wanted a little less stagger. If 235's will fit in the front this might be perfect!

How sure are you that this won't rub when the suspension is fully compressed?

fourtailpipes · 04-18-2009, 10:37 PM

well i'm not lowered, but i did a LOT of cranking the wheel, as well as high speed offramps to scrub the tires and test the fit, and i didn't get any rubbing. every tire's different, but i'd say you're in the clear, especially if you have your alignment pins removed for more camber. the camber is set at completely stock in the pictures above.

arrutled · 04-19-2009, 08:35 AM

that ballooniness is just that specific tire I bet. I had my 245's on my fronts for a good ten minutes cause of some morons at a tire shop. it fit on the wheel. looked funky. I didnt feel any rub, but then they correctly mounted the fronts on and they told me the 245s were rubbing. So, I wouldnt try it.

fourtailpipes · 04-19-2009, 08:41 AM

i think you're right... these tires have quite a round shoulder profile. the tire place told you that the 245's were rubbing? did they drive the car? if not, i'm guessing that means they were touching the strut not the fender?

ssabripo · 04-19-2009, 11:17 AM

Quote:

Originally Posted by fourtailpipes

the 2nd picture shows the rear pretty closely... even with more fender rolling, i seriously doubt there's 10mm to play with.

I'm pretty certain they will.
I'm running 10mm right now on 245's, and no rubbing with about 2mm to spare, so running 255 + fender rolling will most certainly fit.

But I wanna see a close up if you can get one

arrutled · 04-19-2009, 11:27 AM

Quote:

Originally Posted by fourtailpipes

i think you're right... these tires have quite a round shoulder profile. the tire place told you that the 245's were rubbing? did they drive the car? if not, i'm guessing that means they were touching the strut not the fender?

Yeah it was on the struts.

m7ammed · 04-19-2009, 11:28 AM

how much error do you get on the speedo because of the new sizes?

arrutled · 04-19-2009, 01:56 PM

the second number is the aspect ratio which is the sidewall height as a percentage of the width. It will be off by about 3 mph. so when your speedo says your going 73 you are only going 70.

fourtailpipes · 04-19-2009, 10:43 PM

that's not right... here's how you do this calculation: compare the outer diameter of the tires... oem runflats in 245/35-18 have a 24.8" diameter compared to 25.0" on the 255/35-18 RE01R. 25.0/24.8 = 1.008 or an 0.8% increase in diameter and rollout. because it's an increase in diameter, the car will slightly underestimate my speed and distance. the speedometer will register 0.8% too low, as will the odometer. theoretically, it will read 49.6 mph when i'm actually traveling 50.0 mph, or 99.2 mph when i'm going 100.0 mph. the odometer will lose one mile for every 125 miles i travel. (0.008 / 1 = 125). this rate of error is smaller than the typical error already existing in the onboard computer, so this is purely a theoretical error.

m7ammed · 04-20-2009, 04:16 AM

Quote:

Originally Posted by fourtailpipes

that's not right... here's how you do this calculation: compare the outer diameter of the tires... oem runflats in 245/35-18 have a 24.8" diameter compared to 25.0" on the 255/35-18 RE01R. 25.0/24.8 = 1.008 or an 0.8% increase in diameter and rollout. because it's an increase in diameter, the car will slightly underestimate my speed and distance. the speedometer will register 0.8% too low, as will the odometer. theoretically, it will read 49.6 mph when i'm actually traveling 50.0 mph, or 99.2 mph when i'm going 100.0 mph. the odometer will lose one mile for every 125 miles i travel. (0.008 / 1 = 125). this rate of error is smaller than the typical error already existing in the onboard computer, so this is purely a theoretical error.

what about the fronts? or speedo doesn't read speed from the front?

arrutled · 04-20-2009, 05:24 AM

I was just going based on the fact that I was running those diameters over the winter and my speedo was off by 3, but I guess that was my imagination. I think our speedo's are off already though so who cares!

fourtailpipes · 04-20-2009, 08:30 AM

the speedo/odo read rear axle speed. and you're probably right about the car being off by a couple/few MPH at 70... which means that a change of under 1% is well below the inherent error in the car's metrics anyway.

Bdh821 · 05-02-2009, 10:57 AM

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

04-18-2009, 09:14 AM	#1
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	235/40-18 & 255/35-18 on OEM wheels mounted my re01r 235/40-18 & 255/35-18 on stock staggered wheels. no rubbing. excuse the dirty wheels. Attached Images
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04-18-2009, 09:18 AM	#2
C4747Z Second Lieutenant 12 Rep 221 Posts Drives: VO 1M & M5 Competition Join Date: Oct 2008 Location: Long Island, NY iTrader: (0)	How does the car drive? what kind of tires did you put on the car?
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04-18-2009, 12:41 PM	#3
ptack Brigadier General 269 Rep 4,470 Posts Drives: 135i Join Date: May 2008 Location: NJ iTrader: (0) Garage List 2008 135i [6.50]	Nice that they fit, but they seem to look a little balloonee. __________________ 135i, SGM, Coral, Sport Package, Auto, Premium Hifi, USB/ipod, Apex EC-7s, PPK Stage II
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04-18-2009, 06:25 PM	#4
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	they're bridgestone potenza re01r 235/40-18 and 255/35-18. they're for go, not show, and i suspect that i could have done 245 up front without issue. Last edited by fourtailpipes; 04-18-2009 at 06:40 PM..
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04-18-2009, 06:37 PM	#5
ssabripo HALA MADRID! 940 Rep 2,879 Posts Drives: camels & donkeys Join Date: Jul 2005 Location: Plantation, Fl iTrader: (7)	can you take some cleaner and close up pics of the rears? thanks in advance. gonna be mounting mine next week, but running 10mm spacers in the rear, so I suspect some rubbing to occur. __________________ F87 M2 Competition, Sunset Orange, Exc, DCT. SOLD F80 M3 Mineral Grey/Sakir Orange, Exc, DCT... ED 6/2015 SOLDE90 M3, Interlagos Blue / M individual two-tone, ZCP, ZP2, ZCV, DCT, ED.
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04-18-2009, 08:56 PM	#9
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	the 2nd picture shows the rear pretty closely... even with more fender rolling, i seriously doubt there's 10mm to play with.
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04-18-2009, 10:14 PM	#10
lib Major 141 Rep 1,401 Posts Drives: <This space for rent> Join Date: Apr 2008 Location: ATX iTrader: (0)	Hmmm.... I was about to buy a set of Direzza Star Specs in 225/40-18 & 255/35-18 but wanted a little less stagger. If 235's will fit in the front this might be perfect! How sure are you that this won't rub when the suspension is fully compressed?
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04-18-2009, 10:37 PM	#11
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	well i'm not lowered, but i did a LOT of cranking the wheel, as well as high speed offramps to scrub the tires and test the fit, and i didn't get any rubbing. every tire's different, but i'd say you're in the clear, especially if you have your alignment pins removed for more camber. the camber is set at completely stock in the pictures above.
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04-19-2009, 08:35 AM	#12
arrutled Colonel 104 Rep 2,474 Posts Drives: Olsa Join Date: Jun 2008 Location: Western Mass iTrader: (0)	that ballooniness is just that specific tire I bet. I had my 245's on my fronts for a good ten minutes cause of some morons at a tire shop. it fit on the wheel. looked funky. I didnt feel any rub, but then they correctly mounted the fronts on and they told me the 245s were rubbing. So, I wouldnt try it. __________________ AW 135i w/ blackette, performance short shift kit, BMW alarm, Performance rotors, APEX ARC-8 wheels, Direzza Star Spec 235/275, Dinan stage 3 suspension, M3 wishbones/tension rods/front sway/rear subframe bushings and thats all folks!
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04-19-2009, 08:41 AM	#13
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	i think you're right... these tires have quite a round shoulder profile. the tire place told you that the 245's were rubbing? did they drive the car? if not, i'm guessing that means they were touching the strut not the fender?
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04-19-2009, 11:28 AM	#16
m7ammed Captain 210 Rep 959 Posts Drives: 2019 M2 Competition Join Date: Nov 2008 Location: Saudi Arabia iTrader: (0)	how much error do you get on the speedo because of the new sizes? __________________ Instgram: @m7m_photo
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04-19-2009, 01:56 PM	#17
arrutled Colonel 104 Rep 2,474 Posts Drives: Olsa Join Date: Jun 2008 Location: Western Mass iTrader: (0)	the second number is the aspect ratio which is the sidewall height as a percentage of the width. It will be off by about 3 mph. so when your speedo says your going 73 you are only going 70. __________________ AW 135i w/ blackette, performance short shift kit, BMW alarm, Performance rotors, APEX ARC-8 wheels, Direzza Star Spec 235/275, Dinan stage 3 suspension, M3 wishbones/tension rods/front sway/rear subframe bushings and thats all folks!
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04-19-2009, 10:43 PM	#18
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	that's not right... here's how you do this calculation: compare the outer diameter of the tires... oem runflats in 245/35-18 have a 24.8" diameter compared to 25.0" on the 255/35-18 RE01R. 25.0/24.8 = 1.008 or an 0.8% increase in diameter and rollout. because it's an increase in diameter, the car will slightly underestimate my speed and distance. the speedometer will register 0.8% too low, as will the odometer. theoretically, it will read 49.6 mph when i'm actually traveling 50.0 mph, or 99.2 mph when i'm going 100.0 mph. the odometer will lose one mile for every 125 miles i travel. (0.008 / 1 = 125). this rate of error is smaller than the typical error already existing in the onboard computer, so this is purely a theoretical error.
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04-20-2009, 05:24 AM	#20
arrutled Colonel 104 Rep 2,474 Posts Drives: Olsa Join Date: Jun 2008 Location: Western Mass iTrader: (0)	I was just going based on the fact that I was running those diameters over the winter and my speedo was off by 3, but I guess that was my imagination. I think our speedo's are off already though so who cares! __________________ AW 135i w/ blackette, performance short shift kit, BMW alarm, Performance rotors, APEX ARC-8 wheels, Direzza Star Spec 235/275, Dinan stage 3 suspension, M3 wishbones/tension rods/front sway/rear subframe bushings and thats all folks!
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04-20-2009, 08:30 AM	#21
fourtailpipes Major 111 Rep 1,338 Posts Drives: the ladies crazy Join Date: Dec 2008 Location: , Location, Location! iTrader: (0)	the speedo/odo read rear axle speed. and you're probably right about the car being off by a couple/few MPH at 70... which means that a change of under 1% is well below the inherent error in the car's metrics anyway.
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05-02-2009, 10:57 AM	#22
Bdh821 Major 44 Rep 1,265 Posts Drives: 2021 M550i Join Date: Feb 2008 Location: MA iTrader: (3)	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
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