Tires and wheels

[RedFiero]

When I purchased my 85SE 2M6 a few months ago it had 195/14 tires on it. My question is are those the Std Fact size ? I'v noticed that the speedo is not ver accurate and think maybe it's because of the tire sizes. Also can I install a 120mph speedo in the dash and not have to bother with the sending unit?? Thanks for replies..

[mid6]

Originally Posted by RedFiero

When I purchased my 85SE 2M6 a few months ago it had 195/14 tires on it. My question is are those the Std Fact size ? I'v noticed that the speedo is not ver accurate and think maybe it's because of the tire sizes. Also can I install a 120mph speedo in the dash and not have to bother with the sending unit?? Thanks for replies..

The 14" tires are correct for that model and year so that is not the speedo problem.

If you go to a 120mph speedometer you have 2 options.
1 you can replace the one you have with a 120 unit or
2 you can buy an upgrade with the face and resisitor to compensate.
Either way you will probably have to recalibrate.
I hope this helps
EdR

[Ragtop_Renegade]

That's an interesting question, and though I don't know I thought I'd leech off your thread as I have one of my own. When I put a carburated V6 into my 86, do I need to figure out how to drive the speedo or does it operate even without an ECM?

[coop8267]

all you need to change the speedo is the face and crystal. or switch out the whole speedo. no you dont have to calibrate. it is electronic. also for ragtop renegade the sensor for the speedo is on the tranny so if you still have the original tranny then you will be fine

[coop8267]

the original tire size for 85 se is 195-70R14

[RedFiero]

Originally Posted by coop8267

the original tire size for 85 se is 195-70R14

Thankx .I'm running 215/70/14 Dunlop right now but come summertime I think I'll go different size and wheel style. Would like to go back to original wheels but there are too many nice styles out there.

[coop8267]

the speedo is probably inaccurate because of old age. i would think anyway. mine works fine but its only got 40,000 miles and i also have bigger tires than stock so i guess tire size dosent matter

[RedFiero]

Originally Posted by coop8267

the speedo is probably inaccurate because of old age. i would think anyway. mine works fine but its only got 40,000 miles and i also have bigger tires than stock so i guess tire size dosent matter

Ya I'm actually heading to KickHill this Friday and will look into a 120mph speedo assy. This guy has everything there and is super cheap. Just bought a complete engine cradle off him for 100 bucks. The "BARN" is a gold mine of parts for Fiero's.

[coop8267]

i bought my project car for 100 bucks. 84 se. im building a rally car out of it. about half done now

[Ragtop_Renegade]

FYI on tires - changing the width of the tires (first number) will have no effect on the speedo but chainging the profile (2nd number) will. The technical breakdown is that by changing the profile you've also changed the outside diameter, and therfore circumfrence, of the tire. Since the speedo is calibated by GM based on how far the car travels in one revolution of the rear tires, changing the profile will make that distance longer or shorter, therfore throwing the equation off balance. Also when chaging wheel size it is important the original stock profile is kept. To do this you need to use a lower profile tire on the larger rim. For example, if you have stock 195/70 R 14's and purchase aftermarket 15" wheels, you have to make up for the diameter change by using a tire with a lower profile than 70, since you've just increased tire circumfrence by changing the rim diameter. When calculating this, most decent tire places (read: not WAL-MART) will have charts that do the math for you. In the case of the Fiero, though, you're safe knowing you can't have too high a profile as the tire wouldn't clear the rear struts. The width of the tire WILL change the way the car handles, so when in doubt buy a set of junkyard test tires for $25 first and make sure you're happy before you blow $400 on high performance tires. Wider tires can put more stress on the suspension, bearings in particular, so don't be surprised if a component doesn't last as long as it should. One thing to avoid at all costs is offset rims, the kind that make the wheel stick out from the well. Thease put a HUGE amount of stress on the bearings and wear them out quickly. Some guy around here has an early 90's ElDorado with those rims (yes, you guessed it, it does look like crap) and the bearings are so bad the thing sounds like a Boing B52 with bent propellers when it goes around corners.

It's good to know the speedo is driven right off the speed sensor and doesn't need the ECM to work. Thanks coop8267!

[coop8267]

ive taken almost everything apart on 4cyl and had to rewire it myself so if you need anymore help i hope i can help you