peetiewonder

Basically I'm looking for tires for my new rims and am trying to figure out what size tire i want to run. Right now im looking at

285/35, 275/40 on all four, or possibly 255/40 on the front rims.

If anyone has an pix of what a 285/35 or 275/40 looks like on a 9.5" rim i'd greatly appreciate it.

The other thing i'm curious about is sidewall flex. will running a 285/35 on a 9.5" make the tires less responsive or is that balogna?

etnoats

Im running 275/40s on 8.5 in rims but am at work so I dont have a pic right now. 255s on a 9.5 I think would be to narrow and you run the risk of curb rash and popping the bead. 285/35 should look good, and offer the rotaion aspect.

Norm Peterson

255/45 (on its max-width rim), 285/40 or 285/35 maximum tire (on its min-width rim). These are where a 9.5" wheel run up against the Tire & Rim Association maximum and minimum wheel widths. A 255/40 lets you go to 10".

Look at any 2008 or so GT500 except imagine one more inch of wheel diameter which won't affect how the tires fit the wheels. 255/45 front and 285/40 rear, both on 18 x 9.5" wheels. I don't think it was pure coincidence that it ended up like that.

Curb rash is an individual concern; some folks (like one of my neighbors) seem to have lots of trouble with this, others (like me) don't seem to encounter it at all. Popping the bead with a tire mounted on its max-width wheel (or even a half inch wider than that) is a highly unlikely occurrence assuming that you maintain appropriate inflation pressure. Over quite a few years of running tires on wheels at or slightly above max-width for the tire sizes I've never lost any air from even momentary loss of bead seat seal, and that includes autocrossing.


Norm

peetiewonder

is there a reason you tend to run at maximum width wheel? does it go back to the sidewall tension/ strength and give you bettter response?

Norm Peterson

Turn-in tends to be a little sharper, you get a little more ultimate lateral grip if you can keep the outside tires operating at reasonable camber angles, and the general cornering behavior seems to remain a little closer to linear. Break-away probably occurs with somewhat less warning, though I can't ever recall something like that ever catching me by surprise.

Keep in mind that Ford's own 17" and 18" tire/wheel choices were for max-width rims for both of those sizes as well as for the 18" GT500 front setup.


Norm

peetiewonder

appreciate that. i don't feel as bad about staggering on the same size wheel any more.

WeinerDog

Norm, just so I'm sure. For the front, 255/40 and 255/45 are both OK on a 19/9.5" wheel?

peetiewonder

yeah the 255/40 and 45 both fit a 9.5. the 255/40 will be closer to the stock size. ~ 1/4" difference in overall height.

WeinerDog

Cool. The wheels I like come in 9.5 and 8.0. I like the deep dish on the 9.5 and want to put them on all four corners but I don't want 275's on the front.

So, 255/40 on the front and 275/40 on the back? Seems just fine according to http://www.rims-n-tires.com/rt_specs.jsp

One more question: The wheels I like come in the same size except choice of offset, 20mm or 40mm. I'm thinking 40 for the front and 20 for the rear for a bit more width out back (just for looks). I guess this will make the dishes 20mm different, right? But otherwise no problems?

Thanks

peetiewonder

if you are lowered u might run into clearance problems in the rear with a 20 offset. the tires will most likely poke a little bit and rub when u hit bumps. especially on a 9.5 on the 8.0 u should be able to run a 20 offset since the rim isn't nearly as wide.