Square set up 19x9 Boss LS wheels. What tires?

cpembach1 said:

255s are the proper fitting tire on a 9" rim if we are being honest here... the 275 will allow more max grip but more sidewall rollover and less road/steering feel. Since you have 3.31 gears, it wouldn't hurt to go with the shorter tire.

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I should clarify, if you have 9" rims, why not go with a wider tire?

gManTexas said:

I should clarify, if you have 9" rims, why not go with a wider tire?

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While 275/35's or 275/35's are "acceptable" on 9" wide rims (285's are not, BTW), that does not make them the best tire sizes for 9" wide rims unless what you mostly want to do is impress people with your wide tire size number and nothing else (some people are easily impressed that way).

As mentioned (and as OP has already decided), 255-wide tires are really the better choice for 9's. And FWIW I wouldn't put 255/40's on anything narrower than 9's. Ever.


Norm

cpembach1 said:

I think you got a hell of a deal man nice! Post them.

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Just installed. I think a 275/40 in the rear would have looked good. But for all around purposes I think the 255s will work fine. Please excuse my filthy Mustang! Lots of rain here in North Texas lately.

Norm Peterson said:

While 275/35's or 275/35's are "acceptable" on 9" wide rims (285's are not, BTW), that does not make them the best tire sizes for 9" wide rims unless what you mostly want to do is impress people with your wide tire size number and nothing else (some people are easily impressed that way).

As mentioned (and as OP has already decided), 255-wide tires are really the better choice for 9's. And FWIW I wouldn't put 255/40's on anything narrower than 9's. Ever.


Norm

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255/40 fit better on an 8.5, on a 9 they are slightly stretched. It really depends on what youre going to do with the car though. For the 2015's ford put 255/40 on 8.5's

8.5" is the bare minimum width for 255/40's and is definitely "squeezed" down to fit there. A legitimate fit, sure. But this is definitely not a better fit than on 9".

9" is actually the measuring width, which from an appearance perspective provides the sidewall shape that this size tire is supposed to have (a 40-profile tire should never, ever try to look like the 75 and higher profile tires of the 1960's and 1970's). Chances are that the tire was designed to be mounted on its measuring width, with the idea that a little variation either way remains acceptable.


9.5" and 10" would technically be "stretches" for a 255/40, but still acceptable. 9.5" would be at least as acceptable as 8.5", technically.

If what you posted is true, Ford has apparently skewed their priorities in the direction of softer ride quality at some sacrifices in cornering/handling/steering precision. Frankly, I don't understand this shift in thinking, given that in 2008 Ford was mounting the 235/50 tires on 8.5" wide wheels and the 255/45's for the GT500 on 9.5's. 20mm more tire section than my 235's, with probably that much more tread width . . . think GT500-width front tires on regular GT wheels . . . just doesn't sound like a good move for a car with 'sporting' intent.


Norm