cackalak han

I just noticed something over the last few weeks. I went up a tire size (265/65/17 to 265/70/17), which should be around 3.4% increase. Does that actually affect the speedometer at all? Logically, it makes sense that the speedo will show that I am going slower than I actually am.

However, my speedometer is reading very accurate, still. Right by a local elementary school, there is a speed trap w/ a display that shows how fast you're going. It showed 30mph on the speedometer and the same on the speed trap display. On the freeway, they have similar setups (which, if you own a radar detector, you know exactly where those are, since the radar detector going off suddenly scares the crap out of you. ). I noticed that higher speeds were also correct.

What am I missing here?

Paul H.

Your speedo was probably off originally, going to bigger tires made it right.

04 Rocko Taco

Those speed trap devices usually have a built in leeway of 4 mph also. Something about the effectively accurate range of the radar...

CJM

Speedos are generally off some 3mph or so in some vheicles straight from the factory. My camry was like that, car said 35mph but sign said 33.

cackalak han

That's interesting. So if I get clocked going 13mph over, I could be only going 9 over? (factory speedo error + radar gun error) Will this hold water in court?

Side Note: Over here, if you're going 10+ over, your insurance rate goes up. Below 10, you just pay the fine.

04 Rocko Taco

here it is 17+ insurance goes up. But no unless you can prove it in court, and even then, probably not holding water...I think they build in the error of the 4 mph, I thin the radar gun defaults to 4 mph slower than it reads, if it says your going 65, your more than likely going 69, but your speedo will probably say somewhere around 66. THats more like how it works.

Firefightertaco

I don't know how the law is where y'all live but when i got my speeding ticket i was going 15 over(which i really wasn't the cop just marked it up so it would go to court) but anyways i got a lawyer and he said u can file a improper equipment charge every 3 years. that just means somethings not right with your car, and your ticket gets dropped and doesn't show up on insurance or your record u just have to pay the lawyer out the a$$.