Actually, 185/55R15 is a 23.0 inch nominal diameter, which is slightly taller than the stock 195/50R15, but almost identical to the common aftermarket 205/50R15 or 225/45R15s.

(Totally unrelated, but I'm curious why that size? It seems an odd choice.)

Having the wrong sender explains everything. Used green 4.3 senders are cheap, because pretty much every 5-speed NB came with one and they rarely break. Mazda wants an arm and a leg for a new one.

If you've been running around with a sender that's 10% too low, then your odometer is probably also 10% too low for however long it's been in. Might want to factor that into your service periods and mpg calculations.

--Ian

 

Yeah I think mine was $85 shipped from Planet Miata. Might be cheaper if you can find just the gear.

 

I'm pretty sure I have a couple green senders left in my garage. I can check in a few hours when I'm there.

FWIW, Red and Green geared senders were both used on 4.3/5-speed NBs. Red on the cars that came with 15" wheels and Green on the cars that came with 14" wheels.

 

My car is a 2001 Sport, so it came with 16" wheels.

The tires I have on are shorter than the 16's that came on it.

Anyway, the solution was that a 3.9 got swapped in my car without me realizing it, making my math way off. Just need a 4.3, as said above.

As far as why the 185's... that's a whole thread (filled with flames) in itself.

 

 

How much money?

 

Say $30 via Flat Rate Priority?

 

Give me your paypal and money will be yours!

 

Sent you a PM.

 

So, if anyone searches for this problem later...

Just because your car has a 4.3 doesn't mean it came with the 4.3 speedo sender.

 

Yeah this has been good, I haven't put my 3.9 in yet because I want to swap it with a 3.636 R&P before I do. Now I know which speed sensor gear I need.

 

Never trust my memory...found it!
Yellow Box Speedometer Recalibrator 99-05

Rev said it too...yellowbox.