Yesterday I was overtaken by a 16 plate truck on a motorway, nothing odd about that but it was the speed i was overtaken, I was on the limiter 56mph/90kph but this truck flew past me. I was also driving a 16 plate truck it was then i wondered what speed was displayed on that trucks speedo. I get it about Tyre wear and the rotation of the wheel affects the speed but both in brand new trucks, the same make/axel config etc so tread depth shouldn’t be that far out. the truck was from a fairly well known haulier if your a truck driver.
Is it possible when the tacho is calibrated before delivery is it possible to “fix it” so although it shows 90kph on tacho it will do 60mph? is it case of the mechanics getting brown envelopes from hauliers/drivers to be a bit “liberal” with the calibration?
if the “56mph but only actually doing 52mph” story is right does that work at lower speeds too? example in a 30 limit but you could drive past speed camera 35mph and it wouldnt trigger as your “only actually doing 30mph”
Cruise control you don’t write, you don’t call where the bloody hell you been? Like you dropped of the face of the planet. Few other posters like that mind that failed copper think his name was mickyblue. Or shuttlesspanker? Or Rob K?
Mine shows 90kph on dash & 55 on nav so pretty accurate. As said, RM get hold of some flyers and the ones that pass me regular are all rental DAFs from that well known Company from a place that shares it’s name with an area around Manchester…maybe set higher to make up for lack of build quality!
We used to have a fleet of identical Daf CFs, all limited to 85km/h. One of them would show a steady 57mph on the satnav even though the tacho and vehicle speedometer both showed 85km/h.
Cruise Control:
Yesterday I was overtaken by a 16 plate truck on a motorway, nothing odd about that but it was the speed i was overtaken, I was on the limiter 56mph/90kph but this truck flew past me. I was also driving a 16 plate truck it was then i wondered what speed was displayed on that trucks speedo. I get it about Tyre wear and the rotation of the wheel affects the speed but both in brand new trucks, the same make/axel config etc so tread depth shouldn’t be that far out. the truck was from a fairly well known haulier if your a truck driver.
Is it possible when the tacho is calibrated before delivery is it possible to “fix it” so although it shows 90kph on tacho it will do 60mph? is it case of the mechanics getting brown envelopes from hauliers/drivers to be a bit “liberal” with the calibration?
if the “56mph but only actually doing 52mph” story is right does that work at lower speeds too? example in a 30 limit but you could drive past speed camera 35mph and it wouldnt trigger as your “only actually doing 30mph”
just curious.
You could if you wished calibrate it so you were doing 70mph road speed while showing 56 on the Tacho. Basically the higher the k factor the faster the vehicle will go.
I call it “Make the boat mode”. Usually found on Irish trucks rushing to make the ferry. Had it once or twice in fairly fast trucks, they just blat it past.
They set the k factor to the rolling resistance of the tyre, i.e.the amount of tread. To save time and measurements, the dealers have the measurements to hand for all the tyres. Some dealers just limit all to the lowest, some blanket to the highest and some bang in the middle. Upshot being some do 52, some do 60 and most do 55 in the middle ish. I’ve noticed crossroads set everything for the lowest amount of tread, as most brand new ones come out doing 60, while mc truck seem to set the highest, as all ours seem to do 53 on bridgestones, but the msc ones on contis do 55/56. Mercedes and man seem do be the only ones that set them up properly, as they all seem to be bang on 56. Volvo scania and daf seem to take the lazy route
the tread depth does not explain it to me.
315/80 - 22.5 tyre will have a radius of 538mm
increase speed 56 to 60 = a 7.1% increase
to achieve this through tread depth alone would need a depth of 38mm (is that posible even with a regroove ?)
I couldn’t give two foxes what anyone elses’ limiter does. Mine does about 52 even if it can do 56.
People who cry about other trucks’ limiters need a more engaging hobby. Unless that hobby is crying about remapped/chipped trucks having their adblu systems switched off.
Or Stobart Spotting.
when I was at royal mail they were all 56 mph - we got some brand new class 2 rigids and by god nothing passed you - I even questioned it as in road works sat at an alleged 50mph you flew by others.
is this 56mph for lorries a UK rule? Here the speed limit for hgv is 100km/h(62mph).
There is a member of the forum who has BG reg. plates, will be nice top hear where his truck speed is cut off so to speak.
Hi Dolph, yes i`m on BG plates, and my limiter is set to 90 km…when i went to BG for the MOT, they never looked at it…in fact, they never looked at anything , never checked the steering, or lights, or under the vehicle, even though i was over a pit, and with 3 bulbs blown, or even checked the brakes, thats why it was 65 euros with a years road tax…lol
truckyboy:
Hi Dolph, yes i`m on BG plates, and my limiter is set to 90 km…when i went to BG for the MOT, they never looked at it…in fact, they never looked at anything , never checked the steering, or lights, or under the vehicle, even though i was over a pit, and with 3 bulbs blown, or even checked the brakes, thats why it was 65 euros with a years road tax…lol
Yeah, thing are different here(in bad way), I hate that they don’t check properly and care about taxes and money. They checked lights, brakes and possible leaks on my car, but most importantly if I had payed the council vehicle property tax
Dumb as door knobs…mot is a joke here.
OVLOV JAY:
They set the k factor to the rolling resistance of the tyre, i.e.the amount of tread. To save time and measurements, the dealers have the measurements to hand for all the tyres. Some dealers just limit all to the lowest, some blanket to the highest and some bang in the middle. Upshot being some do 52, some do 60 and most do 55 in the middle ish. I’ve noticed crossroads set everything for the lowest amount of tread, as most brand new ones come out doing 60, while mc truck seem to set the highest, as all ours seem to do 53 on bridgestones, but the msc ones on contis do 55/56. Mercedes and man seem do be the only ones that set them up properly, as they all seem to be bang on 56. Volvo scania and daf seem to take the lazy route
Rolling resistance is a totally different kettle of fish and has nothing at all to do with effective diameter (which is what you appear to be talking about). Rolling resistance is all about the energy that is lost due to friction as the vehicle is propelled along the road.
