Will it rub?
(I tried searching with little luck)
Thanks!
(I tried searching with little luck)
Thanks!
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285/30-18 on 9.5ET38
- Thread starter Auraraptor
- Start date
I am trying to find someone who has run that size tire in the rear with either the same or slightly lower offset.
I am interested in buying a set of wheels, but I want to make sure I can mount the tires I want.
I am interested in buying a set of wheels, but I want to make sure I can mount the tires I want.
I have 30 offset on 265 tire and I feel any wider or lower offset will rub.
AD08
The sidewall height is the best to preserve the native over/understeer characteristics with the 215 fronts I plan to run.
Thanks for the help everyone.
I'm with DocJohn on this one!!
The max stock stagger is 215/255 (2002+), the next down is the 1994-2001 which had a 215/245 stagger. Going anything wider than 255 will just make understeer WORSE.
You can mitigate undeersteer by ensuring the overall diameter of the rear wheel is smaller than original rear diameter, assuming all else is the same. More properly stated, one should increase the F to R wheel diameter ratio. Only slightly, of course, as too much will throw off the TC and/or ABS. But you are correct, that will only 'get you so far'.
Looking at the archives, it appears most decrease the F/R ratio when upsizing wheels...bad idea, you will turn the car into an understeering pig.
Now to be completely honest, I haven't yet figured out exactly which front I will use.
Actually, my heart is not set yet on which rear I want to run either! For that matter, I haven't actually bought the wheels (yet)!
So why make this thread? Simple...I found a pair of lightweight (as the seller claims...will check that when I go to pick them up) rear 18x9.5 wheels I actually like.
Their ET was rather low for what I thought would be appropriate for an NSX (ET38).
Now based on the quick 'napkin calculations' I did, I won't be running any wider than 285/30...so if 285/30 will clear I know how much room I will have to work.
If I can't balance out the 285, I will likely end up with a 265 or 255 I can balance out well vs the fronts. I haven't got there yet....
Diameter. (though naturally, yes Width as well)
This is something most don't often realize.
I did that exact test a few years ago with one of my BMWs. I switched from 255/40 to 245/45 rear tire (why? because I wanted to run a 255 in the front of my other car). Realize everything else was the same (they were mounted on identical wheels/same size/offset).
But damn, did the 245s understeer like hell in comparison.
And yes, the other car also undsteered worse now, even though I went from a 245 to 255 wide Front while keeping the rear width the same. This was because the rear wheel diameter was now taller than front.
Moral of that weekend, keep an eye on F/R overall diameter ratios, in addition to F/R width ratios.
This is something most don't often realize.
I did that exact test a few years ago with one of my BMWs. I switched from 255/40 to 245/45 rear tire (why? because I wanted to run a 255 in the front of my other car). Realize everything else was the same (they were mounted on identical wheels/same size/offset).
But damn, did the 245s understeer like hell in comparison.
And yes, the other car also undsteered worse now, even though I went from a 245 to 255 wide Front while keeping the rear width the same. This was because the rear wheel diameter was now taller than front.
Moral of that weekend, keep an eye on F/R overall diameter ratios, in addition to F/R width ratios.
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Diameter. (though naturally, yes Width as well)
This is something most don't often realize.
I did that exact test a few years ago with one of my BMWs. I switched from 255/40 to 245/45 rear tire (why? because I wanted to run a 255 in the front of my other car). Realize everything else was the same (they were mounted on identical wheels/same size/offset).
But damn, did the 245s understeer like hell in comparison.
And yes, the other car also undsteered worse now, even though I went from a 245 to 255 wide Front while keeping the rear width the same. This was because the rear wheel diameter was now taller than front.
Moral of that weekend, keep an eye on F/R overall diameter ratios, in addition to F/R width ratios.
Ok, so the TireRack recommended tire size for a 18x9.5 +38 wheel is a 265/35/18 (which has a diameter of 25.3"). By comparison a 285/30/18 has a diameter of 24.73".
If you read handling guides across the internet, namely these:
http://www.nyracer.com/overunder.htm
http://www.timskelton.com/lightning/race_prep/suspension/corrections.htm
http://www.ffcars.com/FAQ/handling101.html
They all say as an "oversteer correction" to "install shorter rear tires". Correcting oversteer means MORE understeer.
Therefore a 285/30 will cause the car to UNDERSTEER MORE because it is both WIDER and SHORTER than a 265/35/18.
To mean it seems like you're going backwards here, unless Understeer is what you're going for on your NSX. I'm just basing this info on your BMW experience..
Anyway, my suggestions are the following
Go with a 265/35/18 rear tire because:
1) it's proven to work on the NSX.
2) it is taller than the 285/30/18 thereby decreasing understeer.
3) it's recommended rim size is a 18x9.5" wheel (285/30/18 recommended wheel is a 18x10").
4) there are more tires (brands/models) offered than the 285/30/18 tire size (TireRack has 23 tires in the Extreme/Max performance cat for a 265/35 vs only 10 in a 285/30)
5) the tires are LESS expensive than the 285/30/18 counterparts.
6) I can guarantee that it works the with factory TCS.
7) that's exactly what I did on my 18x9.5" ET+38 wheel.
8) it's the right thing to do. :biggrin:
(BTW, the fronts are 215/40/17 and I highly recommend you go that route).:smile:
Hapa88, I like it....you did all the work for me researching the tires. Thanks much! 265 it will be, assuming I successfully get the wheels.
May I ask, what is your front wheel + offset + tire you balance out the 265 rear with?
Looks like a low 30s, 18in wheel if I am not mistaken.
May I ask, what is your front wheel + offset + tire you balance out the 265 rear with?
Looks like a low 30s, 18in wheel if I am not mistaken.
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Hapa88, I like it....you did all the work for me researching the tires. Thanks much! 265 it will be, assuming I successfully get the wheels.
May I ask, what is your front wheel + offset + tire you balance out the 265 rear with?
Looks like a low 30s, 18in wheel if I am not mistaken.
My wheel specs on that track set were:
17x8 +48 with a 215/40/17 Dunlop Star Spec
18x9.5 +38 with a 265/35/18 Dunlop Star Spec
For a while I ran a 5mm spacer on the front making it effectively 17x8 +43 but got tired of dealing with putting it on and making sure it was tight, so I just left it off. The pictures don't have the spacer on it.
Looks like I need a prescription change!
Thank you!
The setup looks great.
Did you notice any change in steering adding the 5mm spacer?
Thank you!
The setup looks great.
Did you notice any change in steering adding the 5mm spacer?
I added the 5mm spacer mainly to match the flushness of the rear. If you notice the front tires are slightly more recessed than the rear. I didn't drive it for more than a few days on the street and didn't notice the 10mm additional track. 5mm per side is pretty minimal.
Thanks!
