bcfx4

How far do bigger tires and a lift throw off our speedometers?
I was on a roadtrip this last weekend up to my buddies cabin. About 400km drive on an open, non busy highway which I've driven many many times in the past. The posted limit is 110 km/h and I usually cruise this stretch at ~130.
Here in British Columbia, if you travel 40km/h over the limit, the police is able to tow your vehicle on the spot and suspend your license for 24hrs.

About half way through the journey, I get pulled over. The officer tells me he clocked me doing 156km/h! No freakin way I would do those speeds (don't need my truck towed). I said whattt?! I'm looking at where my speedo needle would be at that speed, and told him I wouldn't argue with him, but that I really didn't see myself travelling that fast. As he walks away he says, 'might get the tow truck out.'
Anyways, he said that as long as my girlfriend drove the rest of the journey, he wouldn't have me towed. Lucky me I suppose.
Guess my question is, the speedo wouldnt be off THAT much after a lift and tires, would it? (I have 295/70/18s and a 2" front spacer). Maybe the officer was exaggerating (I would have asked to see a print out of my speed had he decided to tow me). Either way, guess I should have my speedo adjusted.

Sinfulpride

If your original tire was 275/65r18s then your speedo is off by 6.8%. So your spedo should of been at ~ 145km/hr for the cop to say you were at 156km/hr. That's still pretty fast LOL

IronJoce

If you where "cruising" at 130km/h on your speedo you were actually doing 139km/h max... not 156

If the cop caught you at 156, you were actually cruising at 146 on your speedo.

Anyway... 139, 146 or 156 you were going too fast ;-)

Cheers

bcfx4

lol definitely agree with the going too fast part. That's why I didn't argue with the guy or put up any fuss, I openly admitted to the guy I was going too fast. I was just shocked to hear the speed he told me. I figured the speedo being off by around the 7% or so that was mentioned before.
But I definitely wasn't going anywhere near 146. Despite admitting that I 'cruised' at the ~130, I'm a pretty conservative and safe driver otherwise. In the last 10 years this is my 2nd ticket. Oh well, lesson learned! On the drive back the cruise was set at just below 110

gouldje

by my calc's that 93.6 mph, i believe the speed limiter is set at 98mph so another words set it at max and let her rip

LaBalaDePlata

iTrader: (3)

sounds like you need a radar

http://www.escortradar.com/passport9500ix-details.php

IronJoce

It's illegal up here and cops can very easily detect it ;-)

13Harleyfan

Thats to bad, the Passport 9500 has saved me a few ticket out here in Texas with long stretches of highway.

Platinum_Sean

Good website to check odometer and speedometer erros when going non OEM size.

http://www.dakota-truck.net/TIRECALC/tirecalc.html

Your odometer is also reading lower too by the way.

You can get the BCM reprogrammed at the dealer or a shop with a programming tool, might have the slip the guy a few Canadian Tire dollars and a Tim Hortons double double. there are pre-defined sizes that can be selected to compensate for the larger sizes.

Craddosk

Maybe in Quebec, but not in BC, AB, SK......