Vf sv6 tyres

[Iankazimierz]

I am wanting to replace the standard 245x45x18 tyres with 245x50x18 to give a bit more vehicle height - 12mm. Any problem with this?

 

[stooge]

it will throw your speedo out a few kph so after you do it check it with a gps app to see how far it is out.

the vf is retarded by about 3kph so when the speedo says 100 you are doing 97~98 so the larger profile tires might make it exact 100 = 100.

 

[PRNDL]

I ran mine against a speed radar in Victoria a couple of years ago and came up with 4km/h difference consistently. 96 at indicated 100. I just set my cruise a bit higher to compensate

 

[stooge]

I ran mine against a speed radar in Victoria a couple of years ago and came up with 4km/h difference consistently. 96 at indicated 100. I just set my cruise a bit higher to compensate

yep it is somewhere in that range, it is an industry practice to make the speedo display about 3% less than the actual speed but that can vary with a few factors.
in every ve/vf i have owned which is about 10 i can do 105 on the speedo in a 100 zone in wa and never get a ticket.

my colorado is the same and i recently bought a zb commodore which is also the same, but changing the tire profile will change that because the rolling diameter is different depending on the profile.

 

[Iankazimierz]

I also heard that increasing the diameter of the tyre can muck up when the auto gear changing occurs. Not sure whether this is correct as i am aware the change is a common occurance

 

[mpower]

yep it is somewhere in that range, it is an industry practice to make the speedo display about 3% less than the actual speed but that can vary with a few factors.
in every ve/vf i have owned which is about 10 i can do 105 on the speedo in a 100 zone in wa and never get a ticket.

my colorado is the same and i recently bought a zb commodore which is also the same, but changing the tire profile will change that because the rolling diameter is different depending on the profile.

it's not "industry practice" it's a legal requirement.

 

[stooge]

it's not "industry practice" it's a legal requirement.

Legal requirement which makes it an industry practice world wide regardless of the laws of each country

the "legal requirement" is not to have the speedo display less than the actual speed.
The requirement is that the speedo must not display greater or less than 4 percent of the vehicles true speed so the manufacturer could legally make the speedo show 100 if you were doing 103 but the "industry practice" is to make the speedo show about 3% more than the speed you are actually doing which is why most vehicles display 100 when you are actually doing 97~98.

 

[Derekthetree]

Surely going from 45 to 50 sidewall only adds 5mm (max) to the ride height?
The 5mm on the other side of the tyre just makes it closer to the arch..

 

[RossK]

Surely going from 45 to 50 sidewall only adds 5mm (max) to the ride height?
The 5mm on the other side of the tyre just makes it closer to the arch..

No, the difference in 45 to 50 series tyres is 5% of the width, not 5mm.
5% of 245 is 12.25mm.
So a 245/45 has a side wall of 110.25mm
a 245/50 has a side wall of 122.5mm

 

[Big Red VF-SII Go-kart]

it will throw your speedo out a few kph so after you do it check it with a gps app to see how far it is out.

the vf is retarded by about 3kph so when the speedo says 100 you are doing 97~98 so the larger profile tires might make it exact 100 = 100.

I set my cruise control to 104km/h in 100km/h zones, which has been measured on the speed gantry on the M1 down in Victoria.
Never had a speeding fine, thankfully, but I did get a red light fine for "dawdling" through a red 0.5sec after it turned in Melbourne last December -- peak hour conga line of cars and it just happened I was near the end and didn't get through in time! Here in the NT, the cruise is ser to 135km/h for 130 (max now, no unlimited speed).