Fitting 11s on all four corners. (Page 1/2)
LS4FieroGuy SEP 29, 12:02 PM
Hey guys. I'm wondering what I would need to do to fit 11 inch wide tires on the front and rear.

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Joshua Seeger

Patrick SEP 29, 03:17 PM

You'd seriously want 11 inch wide tires on the front?
fieroguru SEP 29, 05:31 PM
Widebody or fender flares.

Series8217 is running 265/35/18 front and 315/30/18 rear with 18x9.5 front 18x11 rear wheels.
LS4FieroGuy SEP 29, 05:50 PM
I guess I should ask before anything else how can I prevent plowing through corners? I'm trying to build a Street/Track 88 and think that 11s all around or maybe 12s in the rear and 10s in the front? I'm just seeing what others have done and what would be best for corners at triple digit speeds.
Dennis LaGrua SEP 29, 05:52 PM

quote
Originally posted by LS4FieroGuy:

Hey guys. I'm wondering what I would need to do to fit 11 inch wide tires on the front and rear.




The big question is what do you intend to do with the car and why do you want tires that wide??? You will be adding a lot of un-necessary weight and will need body modifications as well.

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" 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"
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cvxjet SEP 29, 06:13 PM
I want to give you some info...The C8 Vette weighs approx' 3700 lbs...most V6 Fieros weigh between 2600-2800, depending on accessories. My 85 SE V6 (Unloaded) weighed 2580 new- I have added a few things which has increased the weight up to 2640.

The difference between the C8 and my Fiero weigh-wise is a ratio of 1.4:1.....so the C8 Vette tire sizes (Front= 245, rear=305) thru that ratio equal 175 mm wide up front and 215 mm wide in the rear.

I have 205s up front and 225s in the rear....so technically, I have LARGER tires by weight than the C8 Vette! (My tire sizes; 205/55-16 & 225/55-16...These sizes were on several popular cars back in the 80s and 90s so there is a large selection)

Critically, the Vette (And all other modern cars) have very advanced suspensions- LIGHT aluminum components, and electronically controlled shock-absorbers, which can deal with heavy tire & wheel components, while the Fiero has heavier STEEL suspension components and limited shock absorber choices...

To give you an idea of how heavier unsprung and/or rotational weight can affect our cars, I eliminated 3 lbs off of each rear corner and 6 lbs off of each front corner- the car went from driving like a truck to driving very much like a modern car. And it was noticeably quicker in acceleration.

Moral; keep it as light as possible- Like Colin Chapman (Head of Lotus) stated, "To increase performance, Add lightness!"

When I was young all I wanted was really wide tires...but slowly, over time I came to realize that width is not the only consideration for tires. To add 11 inch wide tires to a Fiero you need wide fender flares...The limit (keeping tires in the STOCK fender-wells) is approx' 8-9".
fieroguru SEP 29, 08:18 PM

quote
Originally posted by LS4FieroGuy:

I guess I should ask before anything else how can I prevent plowing through corners? I'm trying to build a Street/Track 88 and think that 11s all around or maybe 12s in the rear and 10s in the front? I'm just seeing what others have done and what would be best for corners at triple digit speeds.



Good tires, tire width stagger close to weight bias, and stiffer sway bars go a long way to eliminating understeer. Running a square tire setup, will cause the car to oversteer.

The 88 Fiero above is a dedicated track car with a 3.4 TDC. Prior to the current setup, he ran 215/45/17 on 17x7 fronts and 275/35/18 on 18x9 rear wheels.

My 88 runs 235/40/17 on 17x8 and 285/30/18 x 18x9.5





LS4FieroGuy SEP 29, 08:46 PM
So from what I'm hearing 9s up front Is plenty. And if I really want to corner better then I would want to mess with suspension rather then huge tires? And I guess I should clarify that I'm building an LS4/F40 Track car and am upgrading the car section by section.

Also @FieroGuru. Did you ever do a top speed test with the LS4/F40 with the Final Drive swap?
fieroguru SEP 29, 09:37 PM

quote
Originally posted by LS4FieroGuy:
Also @FieroGuru. Did you ever do a top speed test with the LS4/F40 with the Final Drive swap?



I haven't done any top speed runs. About 125 is the fastest it has been. More aero mods are needed to help keep it planted.

When I dyno'd it with the 3.55 final drive in 4th gear, it spun the dyno to 150 mph. When I put it back on the dyno with the 3.09 final drive, it will spin it to 170 mph. Revving out to 7200 rpm would push it to 180 mph. I should get new tires (8 years old) before I spin it that high.

The final drive swap was more for driving feel/experience in the lower gears and fuel economy than top speed.
LS4FieroGuy SEP 29, 10:40 PM
@FieroGuru. Honestly you are my biggest inspiration for this build. Seeing what you've done with your Fiero is awesome. And I'm hoping to get my build to break the 200mph mark.