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Has anyone run this size successfully on the back of a GTS without rubbing? If so, what width and offset wheels were you using? I’m on X73 suspension but otherwise stock? Thanks in advance.
 

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I currently have 285/30/20 on the back of my 2014 with 7mm spacers and H&R Sport springs which is even lower than X-73 and no rubbing. Im using the factory 20" wheels, so it will all depend on what wheels you are using and their offset, but yes its possible to get 295 back there. The GT4 comes from the factory with 295/30/20 on the back. You can get even bigger with the right combination of offset. Ive had 11" wide rims with a 305 on my previous P cars
 

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Thanks for the reply!

I have a stock* setup with 20x10" Carrera Classic wheels (ET45) and Sport PASM. Do you think I'd need spacers to avoid rubbing? I was considering the 285/30s, as well, but I noticed the diameter drop from 265/35 is relatively large (-2.2%) compared to the 295/30s (-1.1%). I also went up from 235/35 to 245/35 on the fronts (+1.1%), so I'm concerned about ABS, etc.

* Mine is a 718 Cayman, but, as far as I know, the fitment is the same.
 

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The exact amount of rolling diameter allowable difference required seems to be a mystery. I have heard values from only a few percent to around 10%. I also have upsized to 245/35/20 on the front with my 285/35/20 rears and there is no such problem.

The GT4 runs 245/30/20 up front and 295/35/20 in the back right from the factory so I cannot see that there would be any ABS issues. It also has a 11 X 20 rear wheel with a 50mm offset, so again it will no problem getting a 295 tire back there. It will just depend on your specific wheels offset on whether spacers of any kind would be needed.

You can use a site such as this to play around with different combinations if you know the offset of your wheels

https://www.willtheyfit.com/?width=265&aspect=40&diameter=18&wheelwidth=9&offset=43&width2=265&aspect2=40&wheel_size=19&wheel_width=11&offset2=40
 

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Great! So, in your case, were spacers needed because of your springs? Also, just to confirm, are your rears 285/30 or 285/35?
 

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No, the spacers were just for a wider stance and to push the tire edge out closer the edge of the fender for a better look. 7mm up from and 15mm in back with the stock setup is a common combination, even with X-73 sport suspension and looks good

My car is a little lower that X-73 though so I could induce just a hair bit of rubbing under really aggressive turning when running 10mm wider 275s out back with the 15mm spacers, so I went with 7mm all the way around and then recently went another 10mm wider to a 285 tire in the back and all is still fine. Im at my limits now and any wider tire would need a wider rim and would rub anyway unless I removed the rear spacers.

My setup is 245/35/20 in front and 285/35/20 in back with 7mm spacers on all four corners. here is an image to give you an idea of the stance with my suspension
 

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I think this is the comparison you are making. You should compare your placement to these results.


In this case do you have 17mm (.68") space inside your wheel/tire setup ? And how does it sticking it out another 7mm (.28") work.
I ran 255/35 ET 52 8.5 & 285/30 ET54 10 fit without spacers but rear wheels way in.
Added 7 & 15mm spacers for stance and looks.
 
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