The factory GT 245/45r19 all season tires are 27.7" tall, and the factory 285/35r20 on the GT500 are 27.9" tall, so running a meaty 29" tire isn't out of the question, especially when running 20" wheels. There are a few guys on the forum with 28.5" to 29" rears.

Only the factory 255/40r19 Brembo or Track Pack tires are closer to 27" tall at 27.2", while the base V6 tire, 215/65r17, is 28.0" tall.

 

Guess I'll buy taller tires next time around.

 

Dani,

Check out some pix of the Steeda Q450. Same wheel/tire size selection I went with. IMO it looks good. Tough and even a bit old school.

John

 

Matthew,

It refers to the apsect ratio of the tire...the ratio of sidewall "Height" to tread width as a percentage. Example: in a 275/35/xx the sidewall height will be 35% of the tread width. If the tread width grows and the aspect ratio remains the same, the sidewall height will get taller since it's a ratio. Make sense?

FYI a 30 series tire is lowest aspect ratio that's sold. Even at that the sidewalls are so short in some sizes they're a real b!tch to mount and dismount. They also ride like dupa and you really have to watch for potholes or you're headed for wrecked tire and busted wheel city. Not a real great choice for street driven cars. Stay with 35's or 40's for street use.

John

 

there's a number of 25 series tires on the market. I wouldn't run them but they do exist. after switching out the stock 18's for 20's, I had a few days riding on them before I lowered the suspension. It was surprising how little difference in ride quality there was between a 50 series tire on 18's to 30/35 series in the front/rear on 20's. i can't say enough about how well built the new mustangs are. Some of my previous cars with suspension and rims felt like your kidneys were getting hit with a baseball bat.

From everything I've read and experienced, it really depends on your tire/spring/shock combo. if you go with lowering springs on shock struts and a 30 series tires on bad roads, of course it can get bad. but with the right set-up, you'll find a lot of drivers discussing how the ride quality is comparable and sometimes improved over stock. just my .02 cents. it was comments like yours that made me think twice about doing suspension and 20's on mine. if i would have known the ride quality would have been this good, i would have done it the day I got the car.

 

I would agree, the ride on my 20's with the current tires is much gentler than it was on the stock 19's.

 

There's even 15 series tires now....

 

Thanks for all the help guys! I would be lost without the input.

Matthew

 

+1.....crazy as it sounds.

My 20s and Eibach Pro spriings, are a lot nicer and smoother ride over my Brembo package (19's)

 

One last question. Being my rims are staggered (8.5 and 10s) these tires still work right?

Thanks,
Matthew

 

The fact that they are staggered is the only reason you can do a staggered tire setup.

 

Yeah....brain fart with that question. Not sure what I was thinking.

Matthew

 

Never really thought of this...I always assumed the sizes were the same.

That being said, the Boss and Brembo stangs always looked a little jacked up. I atributed this to to the stiffer springs.
But with the tire sizes now makes sense.

 

Why is it so hard to find 295/30/20 tires???

These are the perfect pair up for 255/35/20 fronts.
And there's an ubundance of these.
You'd figure tire manufactures would at least try and keep their diamters sizes avialble.

I have a set of 20" Shelby KR rims with 255/35/20 up front and 285/30/20 out back on my 2013 GT.
And don't really like the way it looks. The rear gap is way to big. Almost double the front.
And that's with the Eiback Pro kit...1" front drop and 1.5" rear drop.

I'm thinking of evening downgrading to 275/35/20 now just to fill the gap and give room for tire wear.
But by 10" rims may be too wide?
The 285s already look like they are stretched on.

I may just have to give up my directional summer tires and go for the Toyo's all seasons 295s. As they seem to be the most reasonable.

Either that or go with 295/35/20. And keep a 1" difference between the back and the front diamters.

Anyone have the Toyo Poxys and take them out of the track?

 

20 X 9 - 32 offset, 255/35/20 front
20 X 10.5 - 42 offset, 285/30/20 back
Eibach Pro-Kit 1" front - 1.5" back drop with Bilstein shocks & struts.

No problems so far......