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Thread: Will running bigger wheels ruin the handling - track car related.

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    Will running bigger wheels ruin the handling - track car related.

    So i'm looking at making some changes on the 180 this winter, mainly removing the wheels and getting some new more racecar style wheels.

    I'd still like to retain some kind of 'fitment' not really a fan of arch gap, however atm running 17's on the car mean the handling feels compromised a little due to the ride height and stretched tyres a little probably.

    Would running 18's work on a s13 chassis as a track car? Or should i stick to 17's (i need 17's minimum due to brake disc size)

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    Guest Quail's Avatar
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    From driving around (on the road) on 17s and 18s quite a bit, the 17s do feel nicer. Better steering response is noticeable.

    18s certainly don't ruin the handling, but for a track car I'd be sticking with 17s unless I needed the extra brake clearance.

    Fill the arches with more tyre

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    Run 17's with more tyre, winner.

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    Guest ANDY black s13's Avatar
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    I think most of the time attack S bodies run a 18 with a 295/30 tyre like this beast http://www.speedhunters.com/2013/02/...r-suzukis-s15/

    so for ultimate grip/track only I'd go with it must work for them,but as mentioned a 17 gives more sidewall as a compromise for road use
    could even argue that a 18 diameter rim is more metal further outwards,so more rotating weight reducing steering and suspension movement (a tiny bit?)
    but a small gain in ultimate grip from less sidewall/less tyre distortion 18 Vs 17
    I doubt there is much in it tbh if you tested matching sized wheels with matching rubber just 18/17 back to back

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    Yorkshire Rep CMR's Avatar
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    I'd stick to 17's, some light ones at that and get some sticky tyres as said.

    18's are unnecessary weight, and in my opinion look way too big for a 13 chassis.

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    It will work. It won't ruin the handling. A good track is a very uniform surface. Perhaps try a different alignment if you are not happy with the handling at the moment before you spend big bucks changing parts.

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    Quote Originally Posted by CMR View Post
    I'd stick to 17's, some light ones at that and get some sticky tyres as said.

    18's are unnecessary weight, and in my opinion look way too big for a 13 chassis.
    Tyres are pretty heavy too, bet the weight difference isn't much if any.
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    Quote Originally Posted by ANDY black s13 View Post
    I think most of the time attack S bodies run a 18 with a 295/30 tyre like this beast http://www.speedhunters.com/2013/02/...r-suzukis-s15/

    so for ultimate grip/track only I'd go with it must work for them,but as mentioned a 17 gives more sidewall as a compromise for road use
    could even argue that a 18 diameter rim is more metal further outwards,so more rotating weight reducing steering and suspension movement (a tiny bit?)
    but a small gain in ultimate grip from less sidewall/less tyre distortion 18 Vs 17
    I doubt there is much in it tbh if you tested matching sized wheels with matching rubber just 18/17 back to back
    That's fine when running a square tyre. And a 30 profile with a 295 tyre is going to have a decent amount of compliance.

    As soon as you start stretching tyres then the game changes somewhat. So if you have to run stretch for whatever reason, better to do it with a bit more sidewall compliance to begin with otherwise the tyre will be more inclined to slide across the surface than dig in to find grip if it's total stiffness is too high.

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    Quote Originally Posted by piman2k View Post
    It will work. It won't ruin the handling. A good track is a very uniform surface. Perhaps try a different alignment if you are not happy with the handling at the moment before you spend big bucks changing parts.
    My current alignment is more of a compromise due to wheel offsets and tyre stretch to get some kind of 'fitment' for the scene points lol. Im currently -3 camber on the front with 0 toe and 7 caster with -1&1/2 on the rear with a touch toe in.
    Last edited by adamrps13; 26-11-2015 at 14:57.

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    Take a degree out of that front camber and see how it feels.

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    Guest R3K1355's Avatar
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    If it's setup for scene it almost universally feels totally toss to drive, tbh I wouldn't fancy that on a track you'd do yourself a mischief.

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    I run 18's with 235 35 tyres daily but for track i am going to get some 17's so i can run with a bigger sidewall.

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    Why not just try your 18's out on track pointz?

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    17's clad with a track tyre (R888 or similar) as wide as your rim will allow. As for your alignment, those figures sound OK. You could add a touch of toe out at the front if you liked but it's not essential.

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    Quote Originally Posted by R3K1355 View Post
    If it's setup for scene it almost universally feels totally toss to drive, tbh I wouldn't fancy that on a track you'd do yourself a mischief.
    It was never supposed to be set up for grip to start with, i just wanted a clean car with a good stance but still be driveable (i did manage to go round europe and enjoy it) I have the least amount of camber the wheels and tyres would let me have to fit the arches. Its the stretch that kills it and i know that. Which is why i'm changing. I've ordered some wider front wings and rear fenders and gonna stick some fat rubber on the wheels with no stretch.

    Piman i will take a degree out and Blaktooth i will run a touch toe out at the front when the car comes back on the road next year. I had already planned something similar so to hear it from someone who has tracked an sbody

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    it's all about the side wall for grip, look at an F1 tyre, if a tyre cant move and form with the surface the slightest uneven surface will cause it to skip and break free,
    I've got 245/45/17, looks meaty where a 245/40 looks limp in the arch

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    Guest zeppelin101's Avatar
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    Quote Originally Posted by jumpbike View Post
    it's all about the side wall for grip, look at an F1 tyre, if a tyre cant move and form with the surface the slightest uneven surface will cause it to skip and break free,
    I've got 245/45/17, looks meaty where a 245/40 looks limp in the arch
    That's a bad example since F1 is allowed to run such a tyre and so they opt to have high spring stiffness to maintain ride height at all speeds independently of downforce. The tyre is where the vast majority of the cars compliance is located.

    Touring cars (or tarmac rally cars) on the other hand where there is a lot less downforce available don't have anything like the same sidewall on the tyres.

    The tyre is a big and poorly damped spring. In F1 they manage tyre pressures all the time because it is critical to performance. See how upset Mercedes were when Pirelli told them they were running their tyres outside the intended design spec by running them at low pressure. The less pressure it has the less it rebounds off an impact, reducing its spring rate.

    It's a a balancing act and the "right" method largely depends on the base suspension geometry (in terms of managing roll centre), how the car is sprung, chassis stiffness, downforce etc etc

    I'm going to go back a little on what I said further up having read up on suspension design some more...

    It might be that you run a 5kg spring on the car on track and having a squidgy tyre is just going to make the car feel awful mid corner as the contact patch moves all over the place and grip is coming and going all the time. In that instance a stiffer tyre with less roll across the sidewall will likely be more beneficial to constrain the contact patch and get the suspension working. On the other hand if you're running a much heavier spring and a stiff tyre then you really need to be jamming that tyre into the tarmac as hard as possible (ie downforce) to get it working and generate the grip. Much like a LM Prototype or GT.

    If you have low chassis rigidity though (i.e. an S-body without a full cage with door bars in) then the chassis is also a big undamped spring that reduces the effectiveness of the suspension. Imagine putting suspension and wheels on 4 corners of a piece of cardboard and rolling it over some bumps or subjecting it to cornering forces versus doing the same with a steel bar. The cardboard will flex and displace all over the place while the steel bar won't flex at all, it's only displacement is due to transmissibility from the suspension which affects the whole body. The same principle applies to a car chassis. Low rigidity drives you to increase stiffness elsewhere to try and maintain control of the body. You can imagine the downsides...

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    Didn't really notice a massive difference between 17s and 18s on track tbh other than that I was able to run more tyre so had maybe slightly more grip.

    I was running pretty agressive alignment settings although can't really remember what they were due to the lows of the car

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    I will be running 9 and 9.5 for my new wheels and i am definitely going to stick to 17's now Just can't see 18's looking right on the car and i think i can get the right size and offset i want with 17's.

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    Im no racing driver but ive got cars with 17/18 and 20 inch wheels never notice a difference I'd rather have a smaller tyre wall it gets rid of the steering wheel twitch in fast corners.

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