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To 315.... or not to 315?????? SP edition

 
Old Nov 2, 2018, 07:42 AM
  #31  
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Yea I'm talking street/r comp stuff. A 275/35 street tire has some decent stretch on a 10.5. 305/30 would be ideal but that size is pretty nonexistent.
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Old Nov 2, 2018, 08:39 AM
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Originally Posted by ayoustin View Post
Yea I'm talking street/r comp stuff. A 275/35 street tire has some decent stretch on a 10.5. 305/30 would be ideal but that size is pretty nonexistent.
Even an nt01? I ask because I was thinking if I'm gonna run a 275, I might want a 10.5, whereas if I run any other tire a 10" wheel may be best.
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Old Nov 2, 2018, 09:26 AM
  #33  
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Not sure what the section width difference is on an NT01 vs an RC1. I have some 295/30 Hanook TD on a 10.5 wheel as well and those are pretty flush, but I don't see adding another 20mm making it mushroom the sidewall.
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Old Nov 2, 2018, 09:50 AM
  #34  
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To add some data points here I've mounted up a couple sets of R888R's 295/30-18 for buddies on their Vettes and was surprised to see on a 10.5 they appeared to be a little bit pinched. They were certainly more pinched than my 295 A7s on a 10.5 which I found strange and wasnt just bc they have that "lip" protector. I've considered going to 315s but seems new wheels would be required.

Since Dallas seems to have ordered new wheels I'll just wait for him to do the dirty work and copy him And no flags for me so should be even easier, lol!
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Old Nov 2, 2018, 10:18 AM
  #35  
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Originally Posted by heel2toe View Post
To add some data points here I've mounted up a couple sets of R888R's 295/30-18 for buddies on their Vettes and was surprised to see on a 10.5 they appeared to be a little bit pinched. They were certainly more pinched than my 295 A7s on a 10.5 which I found strange and wasnt just bc they have that "lip" protector. I've considered going to 315s but seems new wheels would be required.

Since Dallas seems to have ordered new wheels I'll just wait for him to do the dirty work and copy him And no flags for me so should be even easier, lol!
You're still pretty restricted with a 10.5 wheel, I already rub the inner frame at full lock with a 275 up front with a 20mm spacer. As you go wider from there you'll continue to lose steering angle unless you cut the frame or push things further outboard.
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Old Nov 2, 2018, 12:06 PM
  #36  
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Maybe I'll just do a 10 and whatever tire works.
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Old Nov 2, 2018, 03:10 PM
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Excellent point I somehow completely forgot about. For those running 315's or looking to - is the evox control arm like clearance a must in the steps to get that working? This applies to the 275 tires coming within a couple mm of the frame on full lock typically. Because you would need to push it "out" and that'd be a first step.
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Old Nov 2, 2018, 03:29 PM
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Originally Posted by Balrok View Post
Excellent point I somehow completely forgot about. For those running 315's or looking to - is the evox control arm like clearance a must in the steps to get that working? This applies to the 275 tires coming within a couple mm of the frame on full lock typically. Because you would need to push it "out" and that'd be a first step.
That's one thing I've been trying to sort out in my head. Regardless of what happens, inside of the tire will be pushed inside as far as possible and limited by the strut 100%. You may rub frame or whatever occasionally but its a soft rub and rarely is noticed anywhere other than full lock driving around grid. I will say this, no one has their wheels further inboard than I did before Flags unless they have an upright that also pushes the strut against the fender well. Some running equivalent as me but not possible to get further since my tires were ~3mm off the shock body. I still never had rub issues on course.

What the X arms (or just longer arms) will do is reduce the scrub but sacrifice the SAI. Lower arm moving to X is 20mm longer which comes out to be about 1.8deg more SAI angle but decreases scrub by a lot. I don't know which way is better here, but my thought for now is going with the path of least resistance. I may try it both ways with a billet X arm since it will just swap in replacing my 8/9 arms. But would probably just wait till I had a defect part so Im not testing good products

Now you could move the strut top out as well but that going to be about a 1:1 effect on pushing the wheels out also. Maybe not an issue on track but for AX that just makes for a wider car. Of course Im coming at it from the perspective of narrow and low as possible.
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Old Nov 2, 2018, 07:58 PM
  #39  
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Originally Posted by Dallas J View Post
Dan Stainback and maybe Tim White told me the same thing. Can do 10.5 if just trying to get things sorted for fit but needs more wheel. Though we're talking hoosier here and Austin may be thinking street tire for track.
I don't remember if Tim ran on 10.5 before going wider, but Dan went straight to 12's based on my experience. There was a drastic difference going from a 10.5 to 12 on the 315s.
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Old Nov 2, 2018, 08:15 PM
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I should caveat that this is what they told me, I maybe assumed they tried it. But it certainly could have been 2nd hand info (Maybe from you even...). I just know I got enough crap at nats being on 285s and no front Aero that I can be half assing that part anymore.
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Old Nov 5, 2018, 05:17 AM
  #41  
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Dallas do you know what SAI is at with factory geometry? As long as the longer arms don't push SAI too high they'd be an improvement IMO because they'll provide more camber gain in corner so less static camber can be run.
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Old Nov 5, 2018, 07:30 AM
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This thread is probably worth revisting

https://www.evolutionm.net/forums/mo...angle-you.html

With this table I made looking at the effects of SAI, Caster, Static Camber on instant camber for different steering angles.



Add another ~1.8 to 2 deg to "K" here and its where Id be with long control arms and fully inset strut top.
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Old Nov 5, 2018, 09:42 AM
  #43  
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Per your picture is negative steering angle wheels being steered away from the side measured?

I'll have to read the thread. 20* seems like a ton of SAI. I remember reading somewhere that going far above 10 greatly increases jacking forces and will largely contribute to lifting tires.
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Old Nov 5, 2018, 10:53 AM
  #44  
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Negative would be the the inside tire but doesn't take into account Ackerman. Thought that seemed important in working to see if we were flattening out the inside so it could do more work. So adding caster, SAI, and scrub all seem to be increasing jacking though I haven't looked to see if scrub or ackerman has a bigger effect on jacking.
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Old Nov 16, 2018, 05:19 PM
  #45  
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Subd: Im looking to fit 11s & 315 R7s. Watching closely. Been running 10 295/30 with zero issues.
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