1971 GT6 Mk3 Tyre Pressures

[xebec]

Hi,

I have a 1971 Mk3 GT6 fitted with 175/70x13 tyres and minilites. The handbook states the standard tyre pressures for 155/13 as 24 psi front and 28 psi rear.

Should I be using the same pressures for the wider tyres?

Ken 

[Gully]

I have the same wheels / tyre size / car combination and run 28 psi all round - I found with the lower pressure on the front the steering was heavy and I could feel too much slop / lateral movement on the sidewalls. I'm running Avon fronts and Hankook rears. When the fronts wear out (or more likely get too old!), I'll go for Hankooks there too.

 

Gully

[Pete Lewis]

Its best to keep the front rear balance the same but as the weight of the car is unchanged

 

the same pressure will give the same footprint and tyre width makes little difference

but modern tyres do seem to need a few extra lbs as Gully says , its a bit trial and error to keep the tyre wall stable and not make the ride too hard

 

on old cars the the tyres played a bigger part of the ride quality on moderns the suspension does most of the work and less reliant on tyres to get ride quality

 

as you increase the pressure you reduce the footprint area

Heres a good excuse to keep going out in the car and testing

 

pete

[Colin Lindsay]

I always found the original pressures far too low for modern tyres; my local fitter advised me to bump them all up to 28 or 30. I've run my GT6 and Heralds at that for years with no problems.

[AidanT]

After trials and tests on mine I have found 28 am round best for me but I guess it also depends on your driving style as well, mine is getting more sedate as the years roll by ????

[dougbgt6]

xebec, I don't know what handbook you have but I have a Haynes and it says, GT6 mk3 tyre pressures, 20 front, 24 rear!

 

As Colin says, far too low for modern tyres. I agree with Pete about the weight differential and I've discovered optimum braking is at 26 front and 30 rear.

[xebec]

xebec, I don't know what handbook you have but I have a Haynes and it says, GT6 mk3 tyre pressures, 20 front, 24 rear!

 

As Colin says, far too low for modern tyres. I agree with Pete about the weight differential and I've discovered optimum braking is at 26 front and 30 rear.

Hi Doug,

I too have the Haynes Manual and it states the same as you quote however this information comes from the official handbook for the MK3. The Haynes does state that the handbook that came with the car should be consulted.

I have now set the pressure to 28 psi all round and will see how we go...Thanks...Ken

[Qu1ckn1ck]

Found this post very useful as I have exactly the same question !

[Pete Lewis]

The triumph workshop manual shows for 4.5jwheels and 155 13 radials

gt6 20f 24r

gt6 mk2 24f 24r

gt6plus 24f 24r

 

so haynes is not quite right

 

on that basis mk2 /3 the 28 28 keeps the original F/R balance as you have found and some added pressure aids sidewall stability without wrecking the ride

 

pete