01-18-2018, 07:03 PM | #397 | |
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1. Going square means I can rotate the tires to all four corners. 2. Going square enabled me to get a set of dedicated track day tires that are far more suitable for high speed track duty.
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01-18-2018, 09:04 PM | #398 | |
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01-19-2018, 06:02 PM | #399 | ||
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Can you explain how wider tires give you better grip? I had a hot argument last year with some friends about wider tires and grip. I said of course they give more grip, they are wider and have a larger contact patch. But after some calculations and discussions with engineers and physicists it turns out the contact patch will actually be the same. I'm still trying to figure out HOW it works from a physics standpoint that wider tires give more grip? Is it just because they are taller and thus take more rotational force to spin them? Or something with heat or something? Or just the shape of the contact patch? I mean of course they are better but why? Also if it is because they are taller would it stand to reason 275/40/18 would be better than 275/35/18, at least in the rear? |
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01-19-2018, 06:39 PM | #400 |
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It's the shape of the contact patch that changes/matter, and it appears you weren't talking to tire engineers? This has all been discovered decades ago. The wider the tire, the shorter, front to back, the contact patch but the wider it is. Now you look at the limit of adhesion and how the distribution of the load occurs across that wider contact patch, the distribution of slip across the contact patch, etc, etc. A decent book to read on the subject is: http://insideracingtechnology.com/booktiredescrptn.htm.
A quick excerpt to get started on contact patch theory is here: http://insideracingtechnology.com/tirebkexerpt2.htm
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01-19-2018, 09:52 PM | #401 | |
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The first point of consideration is the tire's construction. The load the tire carries is shared between the inflation pressure through the contact patch area and the tire's carcass. The tire's carcass behaves like a spring. The more the tire carcass needs to deform, the greater load is carried by the carcass. A narrow tire needs to deform more than a wider tire to generate the same contact patch area, hence the narrower tire transfers more load to the carcass and therefore needs to have a smaller portion of the load carried by the inflation pressure, which results in a smaller contact patch area. The second point of consideration is how the tire's tread grips the road. It is a combination of standard friction (grip=normal load times friction coeficient) and the tread elements interlocking with the road surface irregularities. Do to this latter component, a larger contact patch will generate more grip (more elements interlocking with the road = more grip). Naturally, these are not infinite and there comes a point of diminishing return. But as a general rule of thumb, a wider tire will indeed generate more grip. There are however other trade offs from wider tires.
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02-20-2018, 10:13 PM | #402 |
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Just finished a shakedown weekend at Cal Speedway on Hoosier R7's. 275's up front and 295's in back. Car was awesome.
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05-31-2018, 11:25 AM | #403 | |
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You mean your et was net with spacers right? Before doesn't make sense.
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05-31-2018, 11:32 PM | #404 |
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No, I wanted people to know what the whees sizes/offsets were and the sizes of spacers being run with them.
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05-31-2018, 11:37 PM | #405 |
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Not only do we run wider rear tires, we also tried taller rear tires. Did not adversely the ABS at all
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06-09-2019, 02:11 PM | #406 | |
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06-18-2019, 07:29 PM | #407 | ||
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06-26-2019, 12:23 PM | #408 | |
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staggered 275/305
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06-26-2019, 07:47 PM | #409 |
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Looking for suggestions. I bought Apex SM10 19x10 et 25 front and 19x11 et 44 back what tire setup should I get? I was thinking in getting RE71 275Front and 305 back. Just worried too much understeer with 305 in the back. Sadly the RE71 does not have 295 in 19inch. Or should I go with the same set up as stock; 265front and 285 back? Suspension I only have swift springs. No camber plates. This set up will be used 90% for track use. Maybe 10% I'll use it on the street to change the look from the OEM 666m wheels. What do you guys suggest based on track experience. Car is tuned, stage 2 Bm3 OTS.
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06-26-2019, 08:49 PM | #410 |
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For a reference: I went 265/35 front and 285/35 rear. Very controllable with understeer and oversteer. Also works great with really late trail brake.
What I like about RE71's, you can swap the inside shoulder for the outside, basically swap sides on the tire and get twice the track days out of them.
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06-26-2019, 09:09 PM | #411 |
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Let's see how the pictures turn out?
This shows about 5 hours of track time at COTA on a flipped tire, other shoulder was heavily worn. I started taking pictures of my tires every session or two just to track tire wear.
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06-27-2019, 06:22 AM | #412 | |
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06-27-2019, 09:20 AM | #413 | ||
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06-28-2019, 07:30 PM | #414 | |
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It was between 80F-98F when I was on the track at COTA in June a few weeks ago. The tires maybe fell off a little after 10-15 minutes but stayed very consistent. I replaced them with re71s.
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2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct. 2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune Last edited by Suds; 06-28-2019 at 08:57 PM.. |
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