Are my tires too wide???

[cliff724]

So I just put some "like new" tires on my car. I have a 2012 Roush RS1 with 20 x 8.5 wheels. The tires that were on there since I bought it were 255/35/20's. I went with a wider tire...285/30/20. It now feels like my side walls are collapsing or rolling over when I am cornering and when I'm driving on a highway at speeds of 60+, my car will float back and forth like my tires are under pressurized but I know that I have plenty of pressure in them. So I just want to know if the tires are just too wide or could the sidewalls have been damaged when they were installed? Also...what is the widest size tire I can go without any effects? Thanks.

 

[gt5.0coyote]

I think the tires are way too wide. According to Tire Rack a 285/30/20 is supposed to go on a 9.5-10.5 rim. The widest safest tire size I would put on it is a 255 maybe a 265. I would do a 255/35/20, which is the tire that came off of it.

 

[Shelbanator]

I dont see y that should be of any issue as i myself have 2013 shelby with factory 20x9 in the rear with 285/35/20 as far as the side motion could just be the highway itself

 

[gt5.0coyote]

I believe your Shelby OEM rear tire is a 20x9.5.

 

[Shelbanator]

You are right oops

 

[Skrapmetal]

Way too wide for your wheels. https://www.budnik.com/helpful-tire-info/

 

[cliff724]

Thanks for the replies. I was pretty sure that they were too wide but just wanted to get somebody else opinion.

 

[Derek@Lethal]

Post a photo of what the tire looks like on the wheel. I've personally run a 285 width tire on a stock fox body 10 hole wheel (15x7 wheel) so I had much more sidewall and I didn't notice any ill effects. Those cars obviously don't handle too well to begin with but the car did not handle any worse.

 

[SonicDTR]

Entirely depends on the tire. Tire's claimed sizes are all over the place when actually measured.

 

[noldevin]

Definitely too wide. The ideal wheel size for a 285 is 10 inches wide. They work okay on a 9.5. You can squeeze them onto a 9 but it is not at all ideal. I wouldn't try to fit them on anything smaller than a 9.
Drag tires are an exception as you usually don't care much about handling and actually want the sidewalls to flex when you launch.