Tires

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bgkast
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Tires

Postby bgkast » 10 May 2013, 14:33

What size tires is the prototype wearing in the front? From the diary it looks like the rears are 275-40/17, yes?


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Re: Tires

Postby Midlana1 » 10 May 2013, 15:30

205/40-17... but as long as the OD is near 23.5" it doesn't matter much.

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Re: Tires

Postby bgkast » 10 May 2013, 16:47

Any concern reducing the rear diamater slightly? I'm thinking about a 225-50/16 which has a diameter of 24.9 compaired to the "book" rear diameter of 25.7. I am thinking of running a 205-50/15 in front which has a diameter of 23.1.

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Re: Tires

Postby Midlana1 » 10 May 2013, 17:21

Perfect - go ahead and use it. Rear target OD is actually 25.0", so I'm violating my own spec, mostly to see how large a tire would fit.

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Re: Tires

Postby bgkast » 10 May 2013, 22:25

Excellent, thank you.

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Re: Tires

Postby dpkilty » 02 Feb 2015, 12:17

I hate to get too much into the details but I do have a question about tire sizes.

I understand we are looking for 23.5" Front and 25" Rear tire diameters. No problem.

But just how critical are those sizes? Do we need to stay within say +-.5 or +-.25 or what? I see you are running a 25.7" rear tire so it makes me think its not a major deal. Obviously it will change ride height, but are there other suspension/geometry related issues we could see by going to say 24" or 25" tires all around or a 24/25, or 25/26 staggered combo... I am pulling tire sizes and available tires into a spreadsheet and wondering all this. I know I am over-complicating things here though...

Midlana1
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Re: Tires

Postby Midlana1 » 02 Feb 2015, 13:36

The sizes were the design-to values. How much it "matters" as you move away from them all depends upon use, your skill, and how much a few 10ths of a second on-track really matter. Unless it's a track-only car, don't worry about it.

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Re: Tires

Postby dpkilty » 02 Feb 2015, 19:32

Midlana1 wrote:The sizes were the design-to values. How much it "matters" as you move away from them all depends upon use, your skill, and how much a few 10ths of a second on-track really matter. Unless it's a track-only car, don't worry about it.



My use: Mostly street, twisty road driving. Small amounts of autocross/dragcross/possibly drag

My skill: Beginner/Novice. I have autocrossed a dozen times or so over 3 years or so. I try to get out and carve up some curvy roads a few times a month, but nothing too hard. I stay WELL within my limits and those of the car (I reach mine well before the cars...)

A few 10ths... right now that doesn't really matter to me at all. I just want to enjoy the car. I can do that even if I am getting dead last at the local autocross.

There are not too many tracks in my area that have track days. If I want in on that action I could drive for a Chump Car team I help crew for. But they all started in autocross, honing their skills, so that is where I feel is a good place to start as well.

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freakynami
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Re: Tires

Postby freakynami » 03 Feb 2015, 00:12

I did a bunch of research a while back to get as close to the design size as possible. I tried so hard to find the golden solution, match the size, as big a rim as possible for looks, same size rims front and rear (my personal preference), nice low sidewall for looks, just the right amount of "pulled", and available in street tyres (Yokohama S-Drive) and track tyres (Yokohama A-050).

I failed.

But I've got a solid set of options in 17" and 18" ready to go when I get to that stage. I set my margin to within +/-3% and found several options from what is available.

Image

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Re: Tires

Postby Midlana1 » 03 Feb 2015, 07:08

I put down those tire sizes as a "aim for these values" sort of thing, realizing that it's impossible since tire sizes keep changine. Over time, tires just keep getting bigger. In 5 yrs, will everyone be running 24's on their Midlana? Ugh.

The size themselves aren't the problem, it's finding sticky tires in the appropriate sizes.

Just don't worry about it, build the car and enjoy yourself. What I said before, about the track lap times changing slightly, that could well be made up by increasing camber, so about all I can say for certain is that going with different tire sizes will change things - but how it'll chance will be subtle and not always bad.


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