Tyres

mikehzz

Well-Known Member
An interesting thing to keep in mind is that while deflating tyres gives you more traction off road, the opposite occurs on wet tar roads. Race cars increase tyre pressures in the wet because there is less aquaplaning on a higher pressure tyre.
 

discomatt

Well-Known Member
An interesting thing to keep in mind is that while deflating tyres gives you more traction off road, the opposite occurs on wet tar roads. Race cars increase tyre pressures in the wet because there is less aquaplaning on a higher pressure tyre.
Yep very true, learnt that lesson in the days of go carting on slicks on a wet track
 
My 93 Hilux has 205R16 1045 tyres on it. Could I put tyres on it that are a bit higher (larger diameter) to give it a little more clearance?
 

madmonk

Active Member
My 93 Hilux has 205R16 1045 tyres on it. Could I put tyres on it that are a bit higher (larger diameter) to give it a little more clearance?

My understanding is that the you can fit a tyre that is up to 50 mm bigger in overall diameter than the largest tyre size listed on the vehicle's placard. However, depending on your state/territory, this increased clearance is added to whatever you have in the way of a lift kit and if it exceeds a certain value, the vehicle will need an engineer's certificate to be legal.

PS. This article from Bridgestone Tyres has links to each's states Roads and Traffic regulations and might be helpful for more detail.
 

Rhett HS

Well-Known Member
Thanks mate. Which of the numbers refers to diameter in the tyre code (if any?)
In the american(?) code it goes like this.....
35x12.5R15. The first number is the tyre overall diameter.

In the metric(?) code it goes like this.....
235/85R16.
235 is the section width (sidewall to sidewall)
85 is the aspect ratio, meaning the sidewall height is 85% of the section width.

So the calculation goes like this......
235 x 0.85 x 2 ÷ 25.4 + 16 = 32"
 

Petunia

Well-Known Member
205 = wide [8 inches]
R / 85% is profile
16 is rim diameter [inches]

in a 1993 model a 2.8liter de sell? LN106? petrol?
I know an 1998 2.8 de sell was slowish getting there on the standard tyre/rim, but would go anywhere. Changing tyre/rim size/width for the sake of >half< the overall diameter in lift? eg: 30inch standard to 32inch is only one inch gained off the ground, is it worth it?

Experience : 2002 Hilux standard tyres = 205-R-16, so 30 inch high by 8inches wide. changing these to 31 inches high by 10.5inches wide results in 60klm >less< per tank of fuel.

Everyone likes big tyres big ground clearance, maximum salt shaker looks etc. but will anyone tell you that there are down sides?:cool:
 

Rhett HS

Well-Known Member
Once people correct the odometer/tripmeter/speedometer/fuel consumption readout they find larger tyres make little difference to fuel economy one way or the other, and lowering revs at cruise often lowers consumption.

If ruts are made by vehicles with 31" or greater tyres then you may get stuck a lot if you have 30" tyrrs.
 

Petunia

Well-Known Member
Once people correct the odometer/tripmeter/speedometer/fuel consumption readout they find larger tyres make little difference to fuel economy one way or the other, and lowering revs at cruise often lowers consumption.

If ruts are made by vehicles with 31" or greater tyres then you may get stuck a lot if you have 30" tyrrs.
The man has a 1993 hilux, reality check? 1/2 inch 12mm in ruts? c'mon man again reality check? Large diameter ... but add 2.5inches width to each of 4 tyres? reality check?
 
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cam04

Well-Known Member
An interesting thing to keep in mind is that while deflating tyres gives you more traction off road, the opposite occurs on wet tar roads. Race cars increase tyre pressures in the wet because there is less aquaplaning on a higher pressure tyre.
It’s a double edged sword, you still get more traction on wet tar with lower pressures, but yes, with standing water a car/go kart tyre will aquaplane easier at lower pressure due to the flat middle section of the footprint deforming up over the water and losing contact with the road.
Round profile tyre racers (bicycles/motorcycles) do reduce pressures for traction and sidewall warmth in the wet because they don’t aquaplane (as much).
To that end, I’d argue for example, that a 4wd with muds on will gain a traction benefit from lower pressures in the rain so long as it isn’t driving through standing water deeper than it’s tread depth. God help you when you hit a deep puddle though haha.
 

Rhett HS

Well-Known Member
The man has a 1993 hilux, reality check? 1/2 inch 12mm in ruts? c'mon man again reality check? Large diameter ... but add 2.5inches width to each of 4 tyres? reality check?
Have you driven the Border Track with other vehicles? Its a good way to see how much difference diff clearance makes in ruts. If the diffs clear you tend to keep going, if they start scraping its a lot of resistance and progress is much harder or impossible.

I reckon having wider tyres also helps keep the diffs high, they pick up extra height available towards the edges of the ruts.

If you have a number of different vehicles in a group you learn that every bit counts.
 

Petunia

Well-Known Member
Have you driven the Border Track with other vehicles? Its a good way to see how much difference diff clearance makes in ruts. If the diffs clear you tend to keep going, if they start scraping its a lot of resistance and progress is much harder or impossible.

I reckon having wider tyres also helps keep the diffs high, they pick up extra height available towards the edges of the ruts.

If you have a number of different vehicles in a group you learn that every bit counts.
Other People? Reality check, I am about as popular as an airbag on a motorcycle. No one puts up with my over exuberant opinions.

Have you driven on bitumen 312 days a year, and saw how much de-sill that is? The choice is yours, I am just here to oppose every logical choice.:cool:
 
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