speedo is way off..

[babygurl2000]

could it be my rims and tires?
i was going 35 in a 35 mph zone and it felt like I was crawling...:lol:
i just got this GT last saturday and i was told these rims are aftermarket.

anyone know?
http://img460.imageshack.us/img460/9769/house034small1dh.jpg

[Matt95GT]

They are GM wheels (95 GA SE & Sunbird) but not what your particular car should have come with. What size tires are on there? The car should have come with 205/55/R16. Your wheels are 15" though. You can calculate the speedometer difference comparing stock 205/55/16 and what you currently have here:

http://www.miata.net/garage/tirecalc.html

Shouldn't be that far off though... be then again anything under 70 MPH seems crawling to me anymore. :lol:

[Big Joe]

are they 16 inch?

[babygurl2000]

here is the size off the tire

195-65R15

[babygurl2000]

color me stupid i thought the GA originally came with 14 inch tires?

so can someone tell me how much am i off on the speedo?

[Bjornboy81]

the tire calculator says you're only 0.4% off. wierd

[babygurl2000]

Originally posted by Bjornboy81
the tire calculator says you're only 0.4% off. wierd
so whats that calulate to in mph numbers?
like 5 mph off?

so if i am going 35 on the speedo i am really going 30?

[DontPassTheFence]

if its .4 % diff - then you ar eonly travelling .5mph slower than it reads...

My speed is off by 1.2mph, and my wheels are 215/45/R17 as opposed to stock 205/55R16

[babygurl2000]

ok thanks man

i thought thats what it felt like
so i can do 40 in a 35 and be safe

lmao :lol:

[Bjornboy81]

percentage people not a set number!!!! :P

If your speedo reads 40 your really doing 40.16 mph. Oh, I forgot to mention its acutally slow, so you're really going faster than you're speedo reads :D

[babygurl2000]

Originally posted by Bjornboy81
percentage people not a set number!!!! :P

If your speedo reads 40 your really doing 40.16 mph. Oh, I forgot to mention its acutally slow, so you're really going faster than you're speedo reads :D
are you sure? you need to take my GT for a spin then
it feels like i am going slow at 35mph..

i mean it feels like I am going 25mph or that slow:roll2:

[Bjornboy81]

No need to roll your eyes at me baby girl!!! =P

Check out the link that Matt posted and plug in the numbers. 0.4% is nothing. There must be something wrong somewhere else. Have someone pace you down the road and compare it to theirs :)

[Matt95GT]

Originally posted by babygurl2000
color me stupid i thought the GA originally came with 14 inch tires?


Only the base model 92-95 SE came with 14". Actually many of the SE's included 15" or 16" as part of option packages. All 94 GT's came with this 16" wheel:
http://www.page-secure.com/merchants/ugap/dbimages/1243.jpg

But you have these:
http://www.ehubcap.com/store/oem/images/alloy%20wheels/6501b%20grand%20am%20wheel.jpg

[babygurl2000]

Originally posted by Bjornboy81
No need to roll your eyes at me baby girl!!! =P

Check out the link that Matt posted and plug in the numbers. 0.4% is nothing. There must be something wrong somewhere else. Have someone pace you down the road and compare it to theirs :)
ok im gona do that then
thanks :D

[babygurl2000]

Originally posted by Matt95GT
Only the base model SE came with 14". Actually many of the SE's included 15" or 16" as part of option packages. All 94 GT's came with this 16" wheel:
http://www.page-secure.com/merchants/ugap/dbimages/1243.jpg

But you have these:
http://www.ehubcap.com/store/oem/images/alloy%20wheels/6501b%20grand%20am%20wheel.jpg
yeah and they are 15s i dont get it?
:jenny:

[Matt95GT]

Originally posted by babygurl2000
yeah and they are 15s i dont get it?
:jenny:

Some previous owner must have swapped them out at some point. Either way... doesn't really solve your speedometer mystery since the tire size is close. My original thinking was someone swapped them out and just put whatever size tire they could find on it.

[tenspeed]

There should be a sticker on the end of the driver door telling you what size tire and wheel the car came with and how much pressure it should have.

My '96 Achieva had 14" wheels.

[babygurl2000]

oh so my tire pressure is off too?

or i need a different tire all together?

[Bjornboy81]

Tire pressure isn't going to make that big of a difference on the speedo. I think Tenspeed was talking more about the tire size :)

Did you try the pacing with another car thing?

[babygurl2000]

not yet but thats the game plan next.

ok thanks for your help guys. i will keep you posted.;)

[tenspeed]

Originally posted by babygurl2000
oh so my tire pressure is off too?

or i need a different tire all together?

Pressure will mostly effect gas milage, handling and tire wear. The sticker on the door will tell you what size the car came with.

It is possible to go to a larger sized wheel but you should keep the same diameter. That's where the tire calculator comes in.

Since the MPH and milage are linked, you could try a measured mile. Many interstates have mileage markers. If your milage is right, your speedometer should be right too.

[babygurl2000]

I am just telling you how it "feels" when the speedo says I am going 35 mph it feels like I am only doing about 30mph or under even..
I am going to have someone ride along next to me and check it out that way too

thanks i will update soon

[born4drivn]

well, just a thought, My car feels like I'm going way slower than when I had my 95 escort, or when I drive my 2000 Vitara, same thing, drive feels much slower. Now I know I'm going the right speed, it's just the vehicle ride itself for me. It's the sportness in my GA. lol. My tires are stock with 195/65/ 15's, same as sunfires, cavaliers etc......

[babygurl2000]

well i havent been able to do this yet.
the weather has been crappy and cold

[babygurl2000]

see my thread in problems and solutions.

[urweak]

if you feel that 35 is to slow, just do 50. that should solve your problem.

[babygurl2000]

if only that was the answer to all my problems..