IS F (2008-2014) Discussion topics related to the IS F model

245 35 19 or 245 40 19 same for rears 30 or 35 ?

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Old 10-22-12, 07:47 AM
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Weapon F
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Default 245 35 19 or 245 40 19 same for rears 30 or 35 ?

I know these two tire sizes are very close 35mm vs 40mm side wall but it seems like when most people up size there tires they are going with 245 35 19 up front and 285 30 19 in the rears why not go with factory side wall size of 40mm up front and 35mm in rears ?
Old 10-22-12, 09:27 AM
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DEMIK
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The 35 and 45 indicates that this tire size's sidewall height (from rim to tread) is 40% and 35% of its section width.
Old 10-22-12, 09:42 AM
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Kramer
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Correct, the second number is an Aspect ration of the tires section width, doing this when upsizing helps create the exact or near exact total roll-out of the OEM tires 'n wheels
Old 10-22-12, 10:09 AM
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Weapon F
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Originally Posted by demik
The 35 and 45 indicates that this tire size's sidewall height (from rim to tread) is 40% and 35% of its section width.
Originally Posted by Kramer
Correct, the second number is an Aspect ration of the tires section width, doing this when upsizing helps create the exact or near exact total roll-out of the OEM tires 'n wheels
Thanks Demik and Kramer I though that was reason, to try to keep as close as possible to factory dimensions. I recently put 245 35 19 Conti Extreme DWS it fits fine but look much smaller then factory 225 40 19 when looking at from profile view much more fender gap then before.
Old 10-22-12, 12:12 PM
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Originally Posted by Weapon F
Thanks Demik and Kramer I though that was reason, to try to keep as close as possible to factory dimensions. I recently put 245 35 19 Conti Extreme DWS it fits fine but look much smaller then factory 225 40 19 when looking at from profile view much more fender gap then before.
It really shouldn't. The stock 225/40 tire has an OD of 26.1", the 245/35 an OD of 25.8". Thats a fender gap increase of just a bit more than .1". If you take into account tire wear, going from old worn tires to your fresh unworn new tires, the OD should actually be a bit taller, but probably too small to notice.

Lou
Old 10-22-12, 07:00 PM
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Originally Posted by lowrideraz
It really shouldn't. The stock 225/40 tire has an OD of 26.1", the 245/35 an OD of 25.8". Thats a fender gap increase of just a bit more than .1". If you take into account tire wear, going from old worn tires to your fresh unworn new tires, the OD should actually be a bit taller, but probably too small to notice.

Lou
Thanks Lou you are 100% right you would think that based on tire wear of stock 225/40, these two tire should almost be the same size, the stock tires are 2yrs old with 24k miles on them the difference between the 40 and 35 correct me if I'm wrong should be between 1/8 to 3/16. I took some measurments and diffenence is roughly about 3/16 between the two tires. I'll send you some pics

245 35 19 or 245 40 19 same for rears 30 or 35 ?-2012-10-22-15.23.40.jpg
Stock tire 225/40
245 35 19 or 245 40 19 same for rears 30 or 35 ?-2012-10-22-15.21.40.jpg
Conti Extreme 245/35
245 35 19 or 245 40 19 same for rears 30 or 35 ?-2012-10-22-15.23.53.jpg
Stock tire 225/40
245 35 19 or 245 40 19 same for rears 30 or 35 ?-2012-10-22-15.19.28.jpg
Conti 245/35
245 35 19 or 245 40 19 same for rears 30 or 35 ?-2012-10-22-15.02.49.jpg
Conti Extreme DWS 245/35
Old 10-29-12, 07:28 PM
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I am also split between 245/35/19 & 275/30/19 vs 245/40/19 & 275/35/19. I am leaning towards the second option listed. I am thinking less gap more comfort. Can anyone tell me why I shouldn't.
I will go with michelin's super sports. Any feedback greatly appritiated.
Old 10-30-12, 07:28 AM
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Gymkata
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Originally Posted by Rossi
I am also split between 245/35/19 & 275/30/19 vs 245/40/19 & 275/35/19. I am leaning towards the second option listed. I am thinking less gap more comfort. Can anyone tell me why I shouldn't.
I will go with michelin's super sports. Any feedback greatly appritiated.
You could run either. I would recommend the shorter tires as they are closer to the stock height. (when comparing to the stock 26" tire height) Your choices are either shorter by .25" front & .5" rear or taller by .7" front & .6" rear. Obviously that is based on the metric size stated on the sidewall, not actually height since each tire brand will vary slightly. There are many on this forum running the shorter sizes without problems...I don't know about the taller sizes.

According to Tirerack, the PSS tires would be either shorter by .2" front and .4" rear or taller by .7" front and .6" rear.
If you really want more sidewall without going too tall, you could get PSS tires in 235/40R19 and 265/35R19 sizes. According to Tirerack, the tread width for 235/40R19 is actually .2" wider than 245/40R19 and the tread width of 265/35R19 is only .2" narrower than 275/35R19. That seems better since they are only taller than stock by .4" front and .3" rear.

Last edited by Gymkata; 10-30-12 at 07:52 AM.
Old 10-30-12, 10:42 AM
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You might want to run 245/35/19 & 275/30/19 if you plan to lower it later, tall profile sidewall is not good for your front fender liner...
Old 10-30-12, 01:03 PM
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Rossi
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Thank you so much Gymkata for your time. I will go with 245/35/19 and 275/30/19.
Thank you linkseal I was gonna put eibach springs in the front to reduce the gap. Good advice too.
Old 10-30-12, 01:06 PM
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For all of you with eibach springs in the front only. Did you have to adjust the sensor for the auto leveling headlights? If yes, how much?
Any feedback is appritiated.
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