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G37x tire/wheel fitment 245/45-19

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Old Sep 19, 2018 | 08:43 AM
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G37x tire/wheel fitment 245/45-19

Does anybody have first hand experience with a 245/45-19 on a 8.5" wide +35 offset wheel?
I'm not lowing my car, but would like to take up a little gap when I put 19" wheels on. Most 245/45-19's are less than an inch larger overall diameter than the stock 225/55-17 with a crap-ton of gap.
I understand speed'O vs real mph will be off.
My wish is to have a flush'ish look, a little less gap and my obvious concern is interference ANYPLACE.

Any input is appreciated, thank you
Matt
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Old Sep 19, 2018 | 12:13 PM
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The ECU apparently has a limit on how much change it accept in rolling diameter. Everyone sez 3%. That's on top of the transfer case limitation of @1% front-to-rear. There are tons of tire calculators on the Interwebs, including this very site.
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Old Sep 19, 2018 | 03:28 PM
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I've always been curious about that - and I don't quite understand why everyone says a 3% variance from stock will cause issues. Going up in size (or down) on all 4 corners is functionally a gearing change, just at the tires. A 3% difference front-rear (even on a 2WD car) makes sense, due to differences in rotational speed (and sensors deciding it's not a good thing), but not on all 4 corners.

So long as he remains the same at all 4 corners, I don't think - at stock height- he's going to have any issues at all (especially with a narrow-ish tire at 245). It's a 27.7 inch diameter tire, over the stock 26.7inch.
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Old Sep 19, 2018 | 05:05 PM
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I'd rather not answer these kind of questions, just because there's not a definitive line that's been drawn. I'd hate to give it a green light then you end up having some issue down the road. 3% difference from OEM has been floating around the site since before I've been here, and while it's hard to pin down evidence that this will create problems I'd tend to stick w/ that figure. Theoretically like Chaos mentioned, it shouldn't cause problems since it is a square setup but w/ all the sensors that are tied together to the traction control, ABS, and other drive systems it's ???.
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Old Sep 19, 2018 | 05:34 PM
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Originally Posted by bPChaos
I've always been curious about that - and I don't quite understand why everyone says a 3% variance from stock will cause issues. Going up in size (or down) on all 4 corners is functionally a gearing change, just at the tires. A 3% difference front-rear (even on a 2WD car) makes sense, due to differences in rotational speed (and sensors deciding it's not a good thing), but not on all 4 corners.

So long as he remains the same at all 4 corners, I don't think - at stock height- he's going to have any issues at all (especially with a narrow-ish tire at 245). It's a 27.7 inch diameter tire, over the stock 26.7inch.

That was my thought exactly, the ECM should only see it as increased wheel speed, the same increased wheel speed in all four corners as well as slippage front to rear side to side and upside down! LOL It doesn't know if the cars traveling faster or if the tires are taller.
IF the 3% rule applies, for whatever debatable reason, I'd still be within tolerance going from 225/55 to 245/45, on the high limit but still < 3%. The 1% rule shouldn't apply with a square setup.

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Old Sep 19, 2018 | 05:40 PM
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Originally Posted by blnewt
I'd rather not answer these kind of questions, just because there's not a definitive line that's been drawn. I'd hate to give it a green light then you end up having some issue down the road. 3% difference from OEM has been floating around the site since before I've been here, and while it's hard to pin down evidence that this will create problems I'd tend to stick w/ that figure. Theoretically like Chaos mentioned, it shouldn't cause problems since it is a square setup but w/ all the sensors that are tied together to the traction control, ABS, and other drive systems it's ???.
I'm with you, I'd be hesitant to say 100% there wouldn't be any issue as well. Staying at stock ride height I don't see clearance issues honestly, but would be an expensive mistake if I bought everything, put it on and there was!
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Old Jun 2, 2019 | 09:08 PM
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Just to confirm, absolutely no issues with 245/45-19 in all four corners. Next up 255/40-19 all around, apx same dia as previous just a little bit more section.
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Old Jun 3, 2019 | 12:49 AM
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On a 8.5 width? That’s a little too much in my opinion it’s going to bulge over the rim. I’m running 245 and it’s more than enough rubber for back roads, and if their is any slippage our X just activates the front wheels and corrects it self
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Old Jun 3, 2019 | 12:51 AM
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It'll bulge a wee bit but wider rubber trumps flexier sidewalls.
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Old Jun 3, 2019 | 08:31 AM
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Originally Posted by Said Amir
On a 8.5 width? That’s a little too much in my opinion it’s going to bulge over the rim. I’m running 245 and it’s more than enough rubber for back roads, and if their is any slippage our X just activates the front wheels and corrects it self
The wheel is wider than the tire with 245’s, one oopsies when rotating in the garage and a wheel falls on its face and you’re beautiful expensive wheel is scarred for life...and that’s when impacts and sockets take flight into the walls! Lol

Just my preference, I’m more comfortable with an ever so slight hint of protection.

ill do a before and after pick tonight before the change.
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Old Jun 3, 2019 | 10:14 AM
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My tires have a lip over my rims so I can set them down on the tire instead of the rim, well I guess it varies from company to company. But go for it, but personally I wouldn’t. But make sure to adjust your tire pressure just Incase of any cupping on the tire, or it will just wear out the middle portion.
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Old Jun 3, 2019 | 10:23 AM
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Absolutely zero issues with putting a 255 on a 8.5" wheel. You could put a 255 on a 7" rim. Hell I just put 275s on a 9" wheel and it's just about perfect for the wheel.

The 10mm difference between a 245 and 255 is so minimal especially when you factor in it's only 5mm on each side.
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Old Jun 3, 2019 | 08:52 PM
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Originally Posted by stealthee
Absolutely zero issues with putting a 255 on a 8.5" wheel. You could put a 255 on a 7" rim. Hell I just put 275s on a 9" wheel and it's just about perfect for the wheel.

The 10mm difference between a 245 and 255 is so minimal especially when you factor in it's only 5mm on each side.
Depends on your use for the tires, if you're really pushing them at speed in the corners that extra sidewall bulge will result in extra sidewall flex and depending on how hard they're pushed could become unstable. That's why there's a recommended wheel width for most all tires, especially performance oriented ones. For a daily driver that's driven aggressive on occasion it should be no problems but YMMV.
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Old Jun 3, 2019 | 10:12 PM
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255/40-19 Toyo Proxys 4+ on Q50 19x8-1/2 wheels

Turned out exactly as hoped for!



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Old Jun 3, 2019 | 10:53 PM
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I ran 255 on the 8" rear duckfeet. Bridgestones had sufficient sidewall stiffness to hide their slightly extra height. Not so sure I'd have like that on the front.
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