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Discussion Starter · #1 ·
Hi,
I just changed my tires from stock to a different size. I am running
* Front: 245/35ZR19
* Rear: 285/30ZR19
These are Yokohama Advan Sports tires. I had them road force balanced, and also had the alignment done. I take a the cars very hard on turns and do a lot of pleasure mountain(hill) driving. The cornering performance has deteriorated a lot. I cannot quantify it, but most turns are 20% slower. Straight line might be a little better, I took off better than my friends E55, which used to be neck to neck earlier.
Once again these are not proper tests, take them with a grain of salt, and I will know more when the roads dry up in Bay Area.
If someone can buy my tires, I will sell them and go back to stock. I think the best thing about F is its ability to corner and losing that makes me feel a little unhappy.
Otherwise the car looks better with the wheels full and there is absolutely no rubbing whatsoever.
I will post pictures once I can clean the wheels a little may next week.
Ash
 

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I love mine as well. No drawbacks that I see.
 

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Discussion Starter · #4 ·
Sorry Lou,
I did not mean to spam the list or hurt someone's feelings. I was concerned about the sidewall and the cornering when choosing a wider profile and I asked you about it twice, in your thread. After doing the experiment and objectively taking it to the same hill, where I have worked for 10years and driven more than 20K miles, raced all kinds of cars up that hill (from Cayman, boxter, S-2000, 997 Turbo, M3, M5, E55, C32, Camry, Honda, Lancer you name it). I can say for sure that the cornering is gone down. It does not mean that the car does not look prettier than before, or the wet traction is not better. I am just stating that the cornering will be affected adversely if one chooses to go wider.
The hill I drive on is 650 Harry Rd. 95120. Going in from Bernal Rd side of it. It is mostly private Rd.
Ash
 

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i'm going out on a limb to say that its your tire choice that is the problem. it is not possible to have less grip from a wider contact patch, all other things equal. although your tires are now heavier then before but that should not matter for much. also, alot of the time "feeling" like you are going slower means you are actually going faster.
 

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Discussion Starter · #6 ·
If the wider tires were better the factory engineers would have put it. If you have a tire wider than the rim which is 9 or 9.5 inches in our case and the tire is 11.5+ inches...then the sidewall does not have as much support and cannot handle the cornering. This is a 1800m track on which we time test it and the car is mostly running at the edge. So it is not a feeling, but an actual number. However it could be that Yokohama Advan Sport tires are not as good as Conti-DW/DWS. In either case it is important to be aware.
 

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Sorry Lou,
I did not mean to spam the list or hurt someone's feelings.
My feelings were not hurt:p I just feel that your putting out wrong information and I wanted to correct it. Again, there must be something wrong with your setup. And, your talking corning here. The front tires play a more important role in corning than the rears, unless the rears are so loose that the car may spin out. Again, this is not about feelings, but accurate information.

Lou
 

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Dude I don't know what your talking about. I have 295's and the handling is so much better it's scary. The engineers didn't do it for profit reasons. It's not feesable to put that wide of a tire on a luxury car. Lexus left it up to us to go wider since the stock tries grip great. As doublexl said a wider tire means a larger contact spot which in turn means it can handel going at faster speeds before losing traction. You must have bought lame tires. Get a set of good tires and you'll change your opionon.
 

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I'm not on factory wheels though
 

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The factory rear wheel is 9" wide and tire size 285/30-19 really shouldn't be run on a wheel narrower than 9.5". Air pressure could be an issue as well.
Wow, I know that's what the tire manufacturer's say, however, there are experts that give a thumbs up on the combo. I had my tires installed at a Discount Tire store after a lengthy discussion with the store manager. I have no tire bulge, and the tread is firmly planted from end to end. And, as I have said, much improved performance.

Lou
 

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Has anybody out there ever had passengers in the back of their ISF after installing 285-30-19s in the rear? Do they rub?

I went thru this exercise when I up-sized the tires on my ES300 and ran into problems, now it's time to up grade the ISF's tires.

And after checking all the tire specs out there, only the RE-11s are soft enough for autocross use... The stock Michelin's on my 2010 ISF squeal like pigs when really pushed in the twisties...

Pete in Aptos, CA
 

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No rubbing whatsoever.
 

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I know Lou's 285's fit firmly on the rear stock rim, but how would a 295 fair? It has the same OD as the 255's that came from factory, and I just wanted to get some input on the pros and cons of a 295 tire, which would be upsizing greatly from the factory wheel. TIA
 

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^^^^IMHO, 295/30s would be going over the edge. I've not see one mounted on an stock ISF wheel, but I have seen a 305/30, and it was not a pretty site. There was severe tire pinch, which IMO would not be safe.

Lou
 

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the tire brand issue is a relevant topic because I have seen huge variations myself. The tire width is nearly subjective when it comes to cross brand variables.

Another thing to think about is that wider tires are typically not wider contact area, but more available contact. Meaning if the patch was wider, you would be dividing the traction force across that patch and you would have less traction per section width. Instead, manufactures put wide gaps to spread out traction and keep the same contact area. 305 on a 19x11 is what I am running now and the traction difference is night and day....there is no slip anymore.

Also keep in mind that when you increase traction, you also increase the force into the suspension...meaning more demand on the springs. So it may requre augmenting the spring rates before you can realize the benefits.
 
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