VF2 Wagon - Tyre pressures

[598rwhp]

Guys, I'm looking for advice re tyre pressures for VF2 V8 Sportswagon. Have just fitted 20inch staggered 8.5 & 10 wheels with Pirelli Dragon 245/35 front and 275/30 rears. Tyre place suggested 40 psi all round - ride feels a little harsh, grip is good. Roads 30% city & 70% rural secondary. Any thoughts ?

 

[Skylarking]

With 70% rural secondary roads, I’d have thought it more prudent to get 18“ (or even 17” if they’d fit) rims and appropriate tyres

With 20“, you’ve got very low sidewalls so it’s a balance between the rims getting pounded when you hit a pothole or ridge (on those back roads) due to having lower pressure or having a harsher ride if you have high pressure.

But fashion... the car does look nicer lower and with 20” rims

(You also don’t mention if you carry loads in the rear or it’s just you in the car... which has some impact on tyre pressure)

 

[598rwhp]

Thanks Skylarking - appreciate the comments and on reflection I should have added that the secondary roads are just those that are not concrete smooth freeways, but pretty good bitumen albeit an occasion repaired pothole. With the previous VF (HSV Baretta 20" with 245/35 rubber) we did 60,000ks up and down the same route without damage so I'm pretty much at peace with the surfaces (not perfect but OK). No load carried in the rear just a few minor tools and an esky.

 

[vc commodore]

Thanks Skylarking - appreciate the comments and on reflection I should have added that the secondary roads are just those that are not concrete smooth freeways, but pretty good bitumen albeit an occasion repaired pothole. With the previous VF (HSV Baretta 20" with 245/35 rubber) we did 60,000ks up and down the same route without damage so I'm pretty much at peace with the surfaces (not perfect but OK). No load carried in the rear just a few minor tools and an esky.

So with you previous set up, if you had no abnormal tyre wear issues, run the pressures you did with that.....

You see, tyre pressures are driver dependant, along with roads travelled and loads carried....Whilst one person might get great tyre wear with one pressure, you might end up with crap tyre wear because of the above circumstances...

 

[Smitty]

Guys, I'm looking for advice re tyre pressures for VF2 V8 Sportswagon. Have just fitted 20inch staggered 8.5 & 10 wheels with Pirelli Dragon 245/35 front and 275/30 rears. Tyre place suggested 40 psi all round - ride feels a little harsh, grip is good. Roads 30% city & 70% rural secondary. Any thoughts ?

have played with pressures on the Clubbie wagon (staggered 20s) and with the Pireliis I find around town the 42F and 36R is the go

You need high pressures on the front to avoid wearing/scalloping of the shoulders of the tyres (which happened with the original ex-factory
Contis despite high pressures)

and the rears? High speed highway stuff (and/or towing.. I tow my Commodore race car) I crank up to 40psi otherwise the 36 for normal
around town is fine.

HTH

 

[598rwhp]

Smitty - thanks for the response. Interesting idea to stop that scrubbing of the fronts. I'm on my 4th VE / VF and it has always been an issue. Changed rubber from Bridgies to Michies to Pirelli but never messed with front wheel pressures - will give it a go = nothing to lose.

 

[598rwhp]

So with you previous set up, if you had no abnormal tyre wear issues, run the pressures you did with that.....

You see, tyre pressures are driver dependant, along with roads travelled and loads carried....Whilst one person might get great tyre wear with one pressure, you might end up with crap tyre wear because of the above circumstances...

Again, thanks - really appreciate getting sensible and non-biased advice.

 

[vc commodore]

Again, thanks - really appreciate getting sensible and non-biased advice.

I've been in the trade for years and I'm familiar with the differences in peoples circumstances and how it effects tyre pressures....Most just say a certain pressure and that's it....

I also recommend using your own tyre pressure gauge to check pressures...Different gauges can read different pressures, so in effect you might not have the pressures you actually want by using varying gauges....Also checking the pressures when the tyres are cold also help maintain the correct pressure too

 

[598rwhp]

Thanks again for the advice & it is good to be able to discuss this with like minded people who value their ride. I have my own gauge and compressor, so at least I have a consistent base to work from and do a fortnightly cold check on each car (including the spare). Only hole in this theory is "is my gauge correct"? Not sure how to verify this!

 

[Skylarking]

Only hole in this theory is "is my gauge correct"? Not sure how to verify this!

On your way home from work, stop at the nearest petrol station to your home and check your hot tyre pressure. To check with those silly auto inflation machines, which are accurate, just connect the hose and it will display the pressure for a few seconds before it starts to either deflate or inflate the tyre. I usually set them to a higher pressure than what I want. So just connect, read and disconnect the hose. Then check your hot tyre pressure again when you get home... Those two readings should be rather close if both gauges are reasonably accurate. If the two readings of the hot tyre pressures are massively different, you may want to cross check with yet at another petrol station.

In any case, absolute pressure accuracy isn’t the aim here. The aim is to have pressure consistency by using only the one gauge and being able to look at your tyre wear to determine if you need to run more or less tyre pressure (or a trip to a tyre shop to get an alignment)...