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      11-06-2012, 02:18 PM   #1

Drives: BSM 1M
Join Date: Oct 2007
Location: dfw

iTrader: (0)

Square setup - how wide can you go

So I've pretty well decided I'm switching to a square setup. 18x10 25et all around. I'm doing this for a myriad of reasons. First I love the way the car handles with this setup. Second, the ability to rotate all tires to all corners will greatly increase tire life. Third, 18s are cheaper than 19s.

The question though is how wide can we go up front. A few people are already running 275/35/18s with stock susp (don't know if they are using camber plates -anyone?). I've got 295s on the back now and I'd like to stay as wide as possible. So, can we get 285s up front and what's it going to take?

Here's some background info:

Front: 245/35/19 Sect Width 9.8" Dia 25.8"
Back: 265/3519 Sect Width 10.7" Dia 26.3"

18" Options:
275/35/18 Sect Width 10.9" Dia 25.6"
285/30/18 Sect Width 11.4'" Dia 24.8"
285/35/18 Sect Width 11.4" Dia 25.9"

One thing to note is the front stock size section width is misleading as it’s based on a 8.5" wheel and we are running 9" wheel. So maybe change that section width to 10.3".

Looking at the difference between the 285/30 and 285/35 the thing that stands out is the overall dia. The 285/35 would be a much nicer looking fit as the dia more closely matches stock. I'm afraid 285/30 may create a pretty large wheel gap with the fender.

It doesn't end there though. Here are a couple other data points:

285/30/18 Tread Width 10.5"
285/35/18 Tread Width 10.1"

So the 285/30 is shorter (dia) but it has a seemingly larger contact patch. This would be good where rubber meets the road but what effect will that have inside the wheel well?

Basically compared to each other:
285/30 short and wide
285/35 tall and narrow

So what will it take to make one of these work? Camber plates seem like a given. Will spacers be required too? One requirement is they still need to fit within the fender or at least not make contact with the outer fender under track loading conditions.

Thoughts, ideas, opinions!

Last edited by robertm; 11-06-2012 at 02:46 PM.