I've never tried wide tires on the front. But I once used 245/60/R14 tires on the rear, for an event. There were no fitment issues, although the tire did come pretty close to the spring perch on the strut. That was an '87 Fiero rear suspension, mostly stock.
But, we probably need to know what you mean by "big" - are you talking sidewall or section? And on stock wheels or aftermarket? What ID?
That's an '88.
Were those 15x8.5 wheels? I've had 16x8 wheels that just barely cleared the strut boss on the hub carrier of my '87. I thought the '88 had about 1/2" more clearance to the strut boss.
I have 285/30-18's on 18x9.5 wheels on my '87 GT. I have coil overs, though. The 285/30-18 is a pretty short tire. I don't know if it would fit under the stock spring perch or not.
I was impressed someone could convince a tire shop to put 265s on a 7" wheel, but they were there. The car was quite squirmy too, which was not confidence inspiring. The picture does not adequately capture the bow in the sidewall, but when you consider it's a 10.5" wide tire on a 7" wide wheel, it doesn't take much imagination.
[This message has been edited by thesameguy (edited 01-07-2019).]
I was impressed someone could convince a tire shop to put 265s on a 7" wheel, but they were there. The car was quite squirmy too, which was not confidence inspiring. The picture does not adequately capture the bow in the sidewall, but when you consider it's a 10.5" wide tire on a 7" wide wheel, it doesn't take much imagination.
That is well beyond the limits of a 7" rim for sure. lol
Years and years ago (Oh god....40 years ago...I'm old as dirt!) I had a Mercury Comet GT (Same as a Maverick) and first put 235/60s and 245/60s on cross-wire ET wheels which were 14 x 6.75" wide....I could drive down a street and wiggle the steering wheel and feel the car squirming on those poor sidewalls....When parked, I could push the rear sideways a full INCH!
Later I found some Appliance Wire mags wheels (Gorgeous!) that were 14 x 8.......If I wiggled the steering wheel I would get a headache from slamming my head into the side glass- The car just TURNED- Instantly!
The front 235/60-14s actually measured out to 252 mm Section width and the diameter/ sidewall ended up slightly less....So the tire was basically a 55 series tire......Wheel width can make a huge difference in tire/suspension/handling performance.....
Factory tires for the 87 and 88 Meras utilized 245 x 50 x 15 for the front and 265 x 50 x 15 for the rears. I have not been able to locate the correct front tires recently so I use the 265s on the front also with decent results. There is some inner fender rubbing with sharp turns at low speeds (thing parking lots) but it is not bad.
I run 225 x 45 x 17 rear and 205 x 45 x17 front on aftermarket rims with the same offset (35mm) as stock but with 1/2" wider rim width. Point is when putting larger tires on a Fiero, rim width, wheel offset, tire width. and tire diameter must all be considered. With an auto shift points can change as well. . In the case of the rear tires, if you are running an engine with OBDII the speedometer and shift points (autos) for larger tires is easy to correct in the software. Not so easy to correct with the stock Fiero setup. I believe that the tires I chose had a very close OD to stock, but adjustments in the PCM on my set up were needed due to the 3800 swap PCM originally calibrated to a different tire size. So if you decide to upsize tires plan to also address the adjustments necessary.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Factory tires for the 87 and 88 Meras utilized 245 x 50 x 15 for the front and 265 x 50 x 15 for the rears. I have not been able to locate the correct front tires recently so I use the 265s on the front also with decent results. There is some inner fender rubbing with sharp turns at low speeds (thing parking lots) but it is not bad.
Nelson
Those are pretty tall... no wonder Meras always looked too high.