OK, here's a question about speedos. IF I consider changing wheels on a SE, I'd like the speedo to be as accurate as possible. So, what size should I calibrate it to? Should it be the "stock" 185/70-13 tire, or the SE stock 205/60-14 size? Was the SE speedo calibrated to that tire, or all all the speedos the same?

Thanks...

 

All speedos are the same. The external diameter of the tires:

Are the same. No "real" difference. Even the '85 SE Rear end ratio of 4.076 to the "regular" GSL 3.909 only has a difference of 4.0972%.

At 60 Mph, a difference of 4.0972% = 62.458 mph.

Well within a margin of error of +/- 5 mph.

 

Can I ask a question about the rear end difference? So, the SE read end of 3.909 makes the speedo read about 2.5 mph too fast? or too slow?


I'm not being **** about this, but 5 mph is a lot in my neighborhood...4 mph cost me one ticket this year already. Doesn't help that the police chief lives 5 houses away either.

 

It's all relative to the speed. It's not 2.5 MPH all the time, it's a 2.5 mph difference at 60.

The difference as I stated, (with all factors being constant) is 4.0972%.

So At:

These are rounded to the nearest 10th of a mile.
So, based on the SE gearing, your speedo would read a teeny, tiny bit higher than you are actually going.

Again, with a rule of thumb of +/- 5 mph for error, you can see that you technically be speeding, So keep 5 mph under the limits to make sure.