16" Wheels

Tyre size is 265/70/R16s

Howard.

Nah Troll81,
bigger tyres will throw the speedo the other way.
speedo will show 100, actual speed will increase.
What Howard was saying was that his speedo was showing 100, actual speed was 90 - 95
Shane

Toyotas seem to alkways read fast eg, tarago at work reads 10ks fast, my old 4runner was doing 94 at an indicated 100. No experience with an 80 series but as others have said get it checked with a gps.
Cheers Pete

I have the identical vehicle and at 100k i would be doing 92-94 depending on how new the tyres were and I have had 3 differnt brands

the tyres u r running are too small for an 80 with 275 x 75 x 16 std or 750 x 16 dependant on model varient...the prado runs 265 x 70 tyres and they are son of land cruiser

ABSOLUTLY, the road is to be shared, hands up everybody who is NOT on holidays and is happy to be FORCED into travelling at 10 Klm below posted speed limit, on open road with favourable driving conditions.
Shane

There's a woman at Tweed Valley/Kingscliffe who has started some idiot campaign to crucify truck drivers she says are driving too close to cars (they're probably there preparing to pass) Says it comes from personal experience. My guess is that she was driving along eating toast/doing her eyebrows/talking on the mobile at 10 kms below the limit. If you don't want to do the limit then get out of the road. CONSIDERATION for other road users is the game.

Have you seen the stickers she hands out for the about tailgating,you have to sit up her rse to read it.
Dave....

Chris it is obvious you do not drive for a living. You may be on a sunday drive , but that poor truckie still has 600ks to do before he gets home if he is lucky
Pete

Shane / Wigger / Dave , you seem to forget that the posted speed limit is just that , 'A MAXIMUM SPEED " allowed by LAW , not a speed that anyone has to do ,yes you can be booked for going too slow and holding up the flow of traffic just as you can be booked for exceeding the limit , what would you realy prefer , arrive to your destination in your own vehicle a moment or 2 later or arrive in an ambulance , choice is yours , responsible or richard cranium, which are you ??

If you have a vehicle capable of doing 100kph and are on a road with a speed limit of 100kph what is wrong with wanting to do that speed & why should you be forced to travel slower be cause someone else doesn't want to do that limit?? That's not being a D/head if you need to travel at the posted speed limit to arrive at your destination on time.
Dave...

Dave,
You may well be capable of 100kph, but is the driver in front of you? Maybe he is more comfortable doing 95kph. Should all drivers be forced to do the speed of the fastest driver? If so, wouldn't trucks be holding us all up?

You aren't forced to do 95kph, go around him. Oh, you can't? Well wait until the next overtaking lane. Even if it is 10ks away, you will be there in 6 min 19 secs at 95 kph. If he hadn't held you up, you'd be there in 6 mins, or just 500 mts earlier. If you got held up to this degree 20 times in your trip, it would cost you about 6 minutes!

I drive alot for my job and I don't see many trucks pulling off the road to let cars past if they are being held up.

Col I have had a lot more trucks pull over for me than caravans and I am on the road most days
Pete

Axel,
The point I was making was how many ROAD users travel around at 90 on open road with favourable driving conditions?
I will use Bruce highway, north from Gympie as an example
This BS about arriving safely is just that, If some one on an open highway that has virtually no speed rated corners and feel that 100 is just not safe has some real driving issues, If I was Towing a large caravan and on holidays I would probably be doing 85-90, with fuel prices punching big holes in my pocket, I'm well aware how much money it will save in fuel, (every one else does up there) mindful of the fact that there will be traffic built up behind me and the fact I don't have to be anywhere in particular, would allow to pass, THAT is sharing the road, not this I'll do 90 on the single lane and then do 105 on the dual lane crap, that's why there is such amount of . .well . . . .emotion, especially from truck drivers, and how many overtaking lanes aren't facing uphill?
I see that some one has done the maths in different distance/time
and there is stuff all difference between the two (90/100) but it all comes down to some one, telling some one else, dictating what speed to travel at, 80, 90, 100 are all in the spectrum of LEGAL and You telling me, we are ALL travelling at 90 today because that's what you think is safe, is EXACTLY the same as me telling you, no, today you will be travelling at 100, because that is safe.
Col88 reply just doesn't make sense, the original thread made reference to the truck wanting to go 100, your quote was, wouldn't trucks be holding us all up?, how?
Everybody' s doing 100!, what about hills I here you say, that's where most of the overtaking (climbing) lanes are anyway.
Shane

Shane ,as I stated previously ,you can be booked for holding up the flow of traffic ,, thing is that you have a 99.9% better chance of being booked for exceeding the posted speed limit than being under the limit , and just as an adjunct to the overtaking lane ect , not to many realise that when overtaking you can be booked if you go over the posted speed limit , don't bother laughing , in QLD it is the law.

Well said Shane, every day I encounter idiots who will speed up to 110 (NSW) on every overtaking lane than slow down to 90 . I dont care if they want to do 90 just dont speed up in the overtaking lanes. No wander truckies get aggro . You do come accross the occassional cowboy but the majority are far better drivers then the average sedan driver. When towing I also travel at 90 to 95 to save fuel, but if I have a truck behind me if their is a straight I will slow down to let them pass,
Cheers Pete

Axel, I'm not laughing.
How many people do you know, or even heard about, get done for going too slow? Its up to the copper's discretion, and what defines too slow?
Knock off some-one speeding is easy, the sign says X your doing more than X here is your photo/ticket, we both agree.
Of course you can get done in an overtaking lane for speeding, the sign says XXX that's all your permitted to do in any state, but why do people feel the need, to overtaking something that's doing speed limit anyway?
Shane

Can you explain the relevance of the 'dopler effect'

Wigger - I'm no physicist but as I understand it GPS receivers display speed and calculate the speed using algorithms in the Kalman filter. Most receivers compute speed by a combination of movement per unit time and computing the doppler shift in the pseudo range signals from the satellites. The speed is smoothed and not instantaneous speed.

From the NAVSTAR GPS User Equipment Introduction document Section 3.7:

GPS receivers typically calculate velocity by measuring the frequency shift (Doppler shift) of the GPS D-band carrier(s). Velocity accuracy can be scenario dependent, (multipath, obstructed sky view from the dash of a car, mountains, city canyons, bad DOP) but 0.2 m/sec per axis (95%) is achievable for PPS and SPS velocity accuracy is the same as PPS when SA is off.

Velocity measured by a GPS is inherently 3 dimensional, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on.

But in my plain speakology...there are no losses/gains through tyre wear or mechanical/electrical devices to interfere with the readout.

...and on the Kalman filtering thing check here

Thanks Patrol 22. I was with you till you got to the "I'm no physicist'bit and then you lost me.
No seriously, that was good stuff and it seems to bear out that GPS speed readings can not be taken as being instantaneous and you need to be on a straight path and at a constant speed(reasonably)

Hi Pixie
Dont know if they were speed limited but they certainly moved out of site pretty quick once they passed me.

Doesn't matter if they can do 150km if there not doing that speed, same as your car can do a hell of a lot over the speed limit if you choose to!!
Dave....

The greatest con job on any road is a truck / bus with a sign proclaiming 100klm speed limited , oops there goes another pink pig flying thru the air ,

Ive often seen it claimed about truckiues flying along. Not saying it doesnt happen but ............ I do most of my driving at night on truck routes and i am yet to see it
105 maybe 110 but thats it
It aint the 70s and 80s any more guys

Davoe , no crap no bull , I have been overtaken by a Greyhound bus with the sign on the back re: 100 klm speed limited when I have been doing 160klm per on the FJ1200 , dead flat road , no tail wind , dead straight road , middle of the day, between Rocky and Sarina.

I've seen it happen to but original post didn't say any thing about trucks speeding so why all the winging about two vehicles who's speedos read they were doing 90/95 in a 100 zone and complained about being held up??
Dave...

If you can't get hold of a GPS, then there's a fiddly way of working out whether you're doing the 100kph the speedo indicates. Find one of those 5km measued strips (like that on the
F3 north of Wyong or the one on the M4) get yourself set up so that you're doing a constant indicated 100 before noting the second hand position on your watch. It should take you 36.6 secs
to arrive at the 1km post. By doing it over the whole 5kms (183 secs) you even out the ' foot' error factor. Simple maths will give you the % error factor and you can then work out what indic speed you need to travel at to be doing an actual 100kph

Even if you use a gps, I think that you need to be on a reasonably straight bit of road.

265/70/16's give overall tyre diameter of 30.606ins.
265/75/16's give 31.649. Therefore 70 profile you are currently using is only 96.704% of speed you will get by going to 75's. How do you know that the speed is"spot on' with the 75's. I hope you're not in to that new fangled GPS stuff. We got rid of the last guy who espoused all that stuff.

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http://www.carbibles.com/tyre_bible_pg2.html

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Yeah, that's why I only went to 3 dec points with above to Doug so that no one would call me a pedant