oi8achevy

heres a pic of 285 40 17s goodyear gcs stuffed on my stock gt wheel, rear only. i like the overstuffed look and its an 11 inch tire which really makes it look tough from behind. i have 255 45 17s on the front. car still handles great although i would not put the 285s on the front as it would make it wander a bit.


[IMG]local://upfiles/68278/704C7CB26F004E59B9105DCB82227F9E.jpg[/IMG]

[IMG]local://upfiles/68278/F115DFF2629C413BB4DFDEB1D47F1674.jpg[/IMG]

waykooljr

The recommended rim width for the 285/40/17's is 9.5-11", your wheels are an 1 1/2" too narrow, that's not good, nor is it safe,even if it looks good.

Plus the diameter is a bit short.

Norm Peterson

Not a good combination. Lots of people do not understand tire tech/engineering very well, so don"t take it too personally . . . please take the following seriously.

They belong on wheels that are at least 9.5"wide. All but one tire model that I looked up (and I looked at quite a few) lists 9.5" as the minimum width for that size(the Pirelli P Zero system allows 9.0").

Given that they"re run-flats, the heavier tire construction might resist being mounted on an out of spec wheel width better because of the extra strength. Or they might not be as good as standard load tires in the same sizeif run-flats generate more heat due to flexing as you drive on them. I don"t know which has more effect.

1.5" below spec is simply too far out of the acceptable range to be making any public suggestions that it is an acceptable thing to do. It"s not.

If it helps any, know that on 10" wide wheels the same 285/40 will look almost an inch wider than it does on your 8"s.

Tire size and wheel width need to be chosen for reasons of proper function. Having a certain "look" has nothing to do with function and should not be part of the tire/wheel decision. (To me, it looks "sucked-in" at the rim, and looks like it was either the result of a poorly informed decision or having to "cheap-out" and not get the rightwheels.)

You already suspect that this combination would be a poor choice for the front, and you are right on that account. The rear is just as important - in some cases more so (because you cannot directly steer the rear wheels to correct where the car is heading).

FWIW, I have seen worse, with wheels more than 1.5" out of spec on both the narrow and wide ends of the acceptable range for the tire size mounted. Not good, and I'm being verypolite.


Norm

whtcanbrwnd04u

Plus theyre on a v6

Norm Peterson

Still hitting the wrong buttons - or they aren't working properly.

28HopUp

I too would be concerned about running a tire on a rim that is 1-1/2" narrower than the minimum recommendation from the tire company. They set their standards for a reason, and running a rim that is too narrow (especially with a short 40 aspect ratio) is asking for trouble IMO. I have 275/50R17 (28" dia) tires on my stock rear Bullitts, and although tire choice is limited to either Nitto NT450's or the Falkens, the 17x8" Bullitts do meet the minimum specs for that size tire. Be safe my friend.

I almost forgot -they're mounted on my V6 brwnboy!!! [8D]

ChiDiddy

i dont know what trouble you guys speak of but I have spoken with lots of tire experts in person about putting a larger tire over the rim size and they all say ther is no safety issue what so ever. i put 315s on my 20x9s a while back and had no problem.

So what if its on a v6? Id do whatever i want to make my car look good if i had a v6? Just b/c its v6 means he cant make his car look nice?his car let him do what he wants.

Nuke

This is a safety issue and has to do with the potential for the tire beadtodismountfrom the rim under severe handling situations. Some tire dealers will tell you anything to sell you tires.

waykooljr

I wouldn't trust the opinion on an "expert" that ignores tire manufacturer specifications.

Norm Peterson

The guy across the counter or back in the shop does not normally count as a "tire expert" when it is basic tire and vehicle engineering issues that are being discussed. Even the sales force at any of the better tire places is not likely to get anywhere near enough in-depth engineering training to discuss this particular matter thoroughly. (Hint: they are financially motivated to say things that make sales)

You need to be talking with somebody from the tire company's engineering staff, and be discussing things like "flex point" and how it moves as wheel width varies, heat generation and how well different regions of the sidewall cope with it, fatigue, maybe tire carcass radial stiffness vs vehicle lateral load transfer distribution, etc.

I have.

BTW, wheels that are only 9" wide are also 1.5" below spec for 315/35. Sure, you can probably get them mounted without too much difficulty and they should hold air, but there is more to it than just that.

And these low-profile tires (45-series and lower) are not even supposed to look like the tall balloon-ey things that your grandfather or great-grandfather had to put on his car because he had no choice. Sidewalls are supposed to be on the sides, not on the "top" as you look down near where the tire contacts the road.


Norm