I'd like to know what the largest wheels/tires are that will fit on my 1987 Thunderbird once I convert to 5-lugs. Wheels/tires that require fender rolling/liner cutting are right out. I plan on running 17x8 or 17x9 Cobra rims in order to fit 13" brakes. I want to be able to rotate the tires; so all 4 will be the same.
What offset/backspacing did factory 14"/15" rims come with? Also, was it the same from 83-88? TrickFlow347 indicates it changed in '87. Link. (http://www.foxtbirdcougarforums.com/showthread.php?p=11098&highlight=backspacing#post11098)
Did the fender/inner liner change significantly between 83-86 and 87-88 cars? I've found all cars use the same steering rack and inner/outer tie rods.
Various wheel/tire threads:
http://www.foxtbirdcougarforums.com/showthread.php?t=127
http://www.foxtbirdcougarforums.com/showthread.php?t=1257
http://www.foxtbirdcougarforums.com/showthread.php?t=2136
Size is really limited if you want to stay the same size at 4 corners....basically 245's on 17x9's is about it. I run a 255 up front on mine but the only reason it fits is because I run the M179 17x9 Cobra R wheel on the front. It has basically .5" more backspace than the more common R58 Cobra R (5.95" BS) so it tucks the wheel/tire in further. That's as big as it's gonna get up front. Outback, 275's are no problem at all.
Did you use 94-95, or 96+ SN95 spindles for the 5-lug swap? How much clearance do you have between the tire and the strut?
I'll probably put in coilovers at some point.
I run 94-95 spindles. The edge of the wheelp lip is 3/8" away from the strut....in other words it's pretty tight.
Backspacing varies with rim width...offset doesn't. The offset was the same from 83-88 on the TBirds/Cougar (same as the 79-93 Mustangs (ex SVO and 93 Cobra)).
My wheels tires aren't as wide as Hawk's, but I have 17x8 95 Cobra wheels on mine. SN-95 spindles on stock 83 control arms in the front and SN-95 axles in the back (same length as the stock Tbird ones). The tires are 245/45 front 255/45 rear. As Hawk states not much more will fit up front, but in the rear there is plenty of room. I'd go 275's in the back, but until I get wider wheels the 255's are fine.
Does anybody know if the 5mm the 96+ SN95 spindles add to the track width pulls the tire away from the strut, or is the strut moved outwards too?
Here is an engineering drawing comparing the 94-95 and 96+ spindles. 96+ is yellow, 94-95 is orange.
(http://www.knology.net/~belchja/95vs96_2.jpg)
Gotta login to view.
Whups. It'll be corrected shortly...
Done
i honestly can't tell from that drawing, but i would say err on the safe side and go with 17x8s all around. It would also depend on how much you lower too wouldn't it? Or you could run a spacer in the front. Wouldn't the wider wheels limit your turning radius more as well? I hit my arms with 17x8s and 235s up front, with 98 spindles. Just a heads up.