My Fiero now uses Goodyear Eagle sport 225 /45 x17 tires in the rear and 205/45 x17 tires in the front. I can no longer find the 205 45 x 17 Goodyear size for the front in the Eagle sport version and am wondering if the same size used on both front and back will work. Also wondering why GM chose to use two difference tire sizes on Fieros Anyone tried same size all around? Results in handling and ride?
------------------ " 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 "
My Fiero now uses Goodyear Eagle sport 225 /45 x17 tires in the rear and 205/45 x17 tires in the front. I can no longer find the 205 45 x 17 Goodyear size for the front in the Eagle sport version and am wondering if the same size used on both front and back will work. Also wondering why GM chose to use two difference tire sizes on Fieros Anyone tried same size all around? Results in handling and ride?
the 88 Tangerine menace used a set of 87 rims with 225 tires. honestly didn't make the handling worse other than the horrible bumpsteer which was corrected with alot of chamber and caster changes. then again we arent tracking it at high speed and power. you have mostly 87s to my knowledge so the wider tires should be fine if you arent pushing it too hard or have the right offsets
Most Fieros had the same size all around, only the 88s had staggered sizes (205 and 215), all other years had either all 215 or all 195, the staggered tires was done for performance, the weight is balanced with more in the rear than front, therefore you need more tire on the rear than front to have a balanced car.
The only problem using the same size tires along with the same offset wheelson an '88, is that the front tires will sit more "out" than the rear tires (due to the 88's front hubs). IMO, that looks awful. I've resolved this issue by using wheels with the proper offset for the front, and then using 25mm (1") hubcentric wheel adapter/spacers on these same offset wheels in the rear. Looks 100% better. I've been using these wheel adapter/spacers on two different Fieros for 15 years, with many of those years on an autocross track, with absolutely no issues at all.
Most Fieros had the same size all around, only the 88s had staggered sizes (205 and 215), all other years had either all 215 or all 195, the staggered tires was done for performance, the weight is balanced with more in the rear than front, therefore you need more tire on the rear than front to have a balanced car.
All GTs 86-88 and the 88 Formula ran staggered tire sizes.
My Fiero now uses Goodyear Eagle sport 225 /45 x17 tires in the rear and 205/45 x17 tires in the front. I can no longer find the 205 45 x 17 Goodyear size for the front in the Eagle sport version and am wondering if the same size used on both front and back will work. Also wondering why GM chose to use two difference tire sizes on Fieros Anyone tried same size all around? Results in handling and ride?
Can you find 215's for the front?
I ran a 215/225 stagger on my Fieros for years with 15 inch wheels. I now run 215/235 stagger on 17's (50 series) on my Formula.
All GTs 86-88 and the 88 Formula ran staggered tire sizes.
No, only the 88s.
85 GT got the 6"wide 14" rims with 215 front and rear, 86-87 got 15x7 215 front and rear, 88 GT/formula got 15/6 205 front, 15/7 215 rear with staggered tires.
My Fiero, 85 GT, tire size 215/60R14 for all, pressure listed front and rear, 125/70d15 spare tire.
My dad's, 86se, exactly the same
[This message has been edited by 1985 Fiero GT (edited 03-07-2025).]
olejoedad is correct about staggered tires on 86-88 GTs.
The fastback cars (and Formula) received: 205/60R15 (front) 215/60R15 (rear)
The tires were staggered even though the wheels were the same.
Oh ok, interesting, I guess that would have only added to the understeer early Fieros have, without other changes to the suspension like a rear sway bar like the 88 got, 84/5 would have had less understeer than 86/7, assuming that more tire=more grip
I ran a 215/225 stagger on my Fieros for years with 15 inch wheels. I now run 215/235 stagger on 17's (50 series) on my Formula.
My wheels have a 36mm offset. I thought that you can't go too much wider than the 225/45 17 rear tires on my 87GT. You are running 235's. That IMO is a tight squeeze with stock struts. Should I try those? .
------------------ " 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 "
My wheels have a 36mm offset. I thought that you can't go too much wider than the 225/45 17 rear tires on my 87GT. You are running 235's. That IMO is a tight squeeze with stock struts. Should I try those? .
The wheels on my Formula are 17x7 with 40mm offset.
Do you have access to the tire/wheel calculator chart for the Fiero?
The 86 and 87 GTs had 205s up front and 215s in back. By the way, comparing the WEIGHT of a C8 Vette to our Fieros (3700 lbs vs 2700lbs) Gives a ratio of 1.37:1....running the Fiero tire sizes thru that gives 281 mm width front and 295 mm rear...Vs the C8s tire sizes of 245 and 305...
Critical for the >>Driving experience<<, keep the tires and wheels LIGHT....heavy unsprung/rotational weight makes our cars drive like TRUCKS....
I don't give a dang about what others think of me- or my car....I want to ENJOY driving it....
Originally posted by cvxjet: I don't give a dang about what others think of me- or my car....I want to ENJOY driving it....
i agree. Driving experience is my #1 priority, looks are secondary.
i have no opinion on tire sizes but i run the stock 15" lace wheels with all four tires the same size, and have found that she handles much better than when she had 14's in the front and 16's in the rear.
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!
The 86 and 87 GTs had 205s up front and 215s in back. By the way, comparing the WEIGHT of a C8 Vette to our Fieros (3700 lbs vs 2700lbs) Gives a ratio of 1.37:1....running the Fiero tire sizes thru that gives 281 mm width front and 295 mm rear...Vs the C8s tire sizes of 245 and 305...
Critical for the >>Driving experience<<, keep the tires and wheels LIGHT....heavy unsprung/rotational weight makes our cars drive like TRUCKS....
I don't give a dang about what others think of me- or my car....I want to ENJOY driving it....
When I went from the 15" to the 17" wheels and tires, and the fieroguru 13" brake kit, I shed weight on all four corners.
You are correct, reducing unsprung weight improves the driving experience.
Dennis, I'm running 17's with a 35mm offset. I run 225-45-R17 on the front and 245-40-R17 on the rear. The reason for the staggared sizes is because the sidewall of the 225-45 almost touches the spring seat of the rear strut. It's been years, but I think the 245-40s scrub the fenderwell liner a bit in a full lock turn when installed on the front. A little more offset would allow for same size tires if the 225-45's were used. I did change the VSS gear and my speedo is almost dead on with the GPS at 70 mph.
My Fiero now uses Goodyear Eagle sport 225 /45 x17 tires in the rear and 205/45 x17 tires in the front. I can no longer find the 205 45 x 17 Goodyear size for the front in the Eagle sport version and am wondering if the same size used on both front and back will work. Also wondering why GM chose to use two difference tire sizes on Fieros Anyone tried same size all around? Results in handling and ride?
Staggered tire sizes are used to match traction to weight on each end of the car. For the tire sizes you currently use, ratio of tread is 48% front and 52% rear. That is likely very close to the weight ratio of your car. My Fiero weight ratio is 44% front and 56% rear, with a 3800SC that added about 100 pounds to the rear from stock.
The Corvette C8, America's second mid engine car from GM, has a weight ratio of 40/60 and has a choice of 245/305 tires for a 46/55 tire ratio, or 285/325 tires for a tire ratio of 47/53.
Wheel size, width, offset and weight all have their place in tire/wheel selection, but a Fiero should be using staggered sizes that are close to the same width ratio as the cars weight ratio.
Looks is just lipstick on a pig, if your car doesn't handle well and you don't enjoy driving it.
[This message has been edited by 87GT3800SC5SPD (edited 03-08-2025).]
I am now running 16 x 7 (38 mm offset) front and rear- the tires are sizes 205/55 and 225/55....This keeps the front tires "Tight" on the rim for good steering response, while adding more width/traction for the rear, where there is more weight and...more Power.
I have done this with all of my cars- same width wheels front and rear, but with wider tires on the rear- has always worked well.
I used to run General Tires because they were >>Cheap<<.....Then started running BFG T/As, then later, with more income went with BFG COMP T/As...But when I swapped the Fiero up to the 16 x 7s, I decided to go back to General, which is now owned by Continental....The General G-Max Tires rate very highly in comparison tests, and are LIGHTER by a few pounds than most Competitors. They drive/handle very well- and hold up pretty good also. I highly recommend these tires.
Also, the 205/55-16 and 225/55-16 sizes were used on several popular cars back in the 90s, so there are numerous choices for these sizes...which means that unlike our 215/60-14s and 205-215/60-15s, there is a good possibility that everyone will continue to make these sizes in high performance rated tires...
[This message has been edited by cvxjet (edited 03-09-2025).]
I am running stock Chromadora wheels on an 88 Mera with coil overs. Due to the unavailability of the front stock 245 x 50 x 15 tires I run 265 x 50 x 15 tires on all corners with minimal issues. Turning is a bit harder from a stop and the front tires sometimes have a slight rub when doing very low speed turns. At one time I also had and 88 Mera with Chromadoras with coil overs with 295 x 50 x 15 on the rear but I could not tell much difference in handling.
