20” Tyre Pressure

[BognorMotors]

Hello all

On 275/35 and 265/40 applications we’ve always gone with and recommended 40psi all round. Recently we’ve been experimenting with different pressures.

We’ve had two t32 Kombi s running Bilsteins and 265/40, one on 36psi and the other on 40psi. Both have covered 12000 in a year.

The rear tyres are worn out on the 40psi van, evenly, but illegal. The other van still has 3mm + left.

Bilstein B14s does increase tyre wear, as more is demanded of them, but running slightly pressures, not only increases ride comfort, but also tyre life.

We are playing around with the pressures on our demo van, running the 275/35 tyre and will report back.

What pressures are you all running, on 20’s and anything to add?

 

[Jeff Goodall]

I have t32 on b14 . 265/40 20 nankang . Run at 36 psi 14k miles on them and still fair bit left . I went with these tyres as recommended by yourself .

 

[Tourershine]

My 19s on my T32 are renowned for chewing out rear tyres. I ran a set of Eagle F1s at 46psi and destroyed them in 4000 miles. I've gone from 46, down to 40, and now 36 on my rears, and still they don't do more than around 7000 to a set of rears. You know my setup because you guys did it, but to anyone that doesn't, B14s on lowest, H&Rs set on stiffest, with a consistent weight of around 400kgs. I drive hard and do play around with my T6 at times, but I'm having to use cheap tyres now, simply because I go through the rears so fast.

 

[Trev P]

Hi all, I am looking for some advice on the correct pressures to be running when towing a twin motorbike trailer with 20" rims.

 

[Daffy]

It all depends on the load on the rear axle, I would say ignore the bike trailer and just set the pressures as you normally would for the weight in the Van as the bike load on the towbar isn't going to be significant in the big scheme of things.

Others might have a different view but I doubt that the 50kg (ish) of nose weight will have much impact.

 

[Littleblackflash]

I agree, the nose weight will only be 50Kg and you'll never notice the difference. I run 41psi on 20" if thats any help.

 

[Trev P]

I agree, the nose weight will only be 50Kg and you'll never notice the difference. I run 41psi on 20" if thats any help.

is that back and front at 41psi?

 

[Oldrat]

An easy test is to feel each of the tyre sidewalls after a run. If they are hot then the pressure needs upping, or the weight reducing. It’s an indicator of excessive sidewall flex which in turn is a cause of blowouts

 

[Trev P]

An easy test is to feel each of the tyre sidewalls after a run. If they are hot then the pressure needs upping, or the weight reducing. It’s an indicator of excessive sidewall flex which in turn is a cause of blowouts

 

[Oldrat]

Applies to any tyre/ vehicle after a run.
As the wheel rotates the sidewalls go from being relaxed through ( say) 350 degrees of rotation until that part of the circumference reaches the (say) 10 degrees where the road is when the sidewall flexes a little. It immediately unforced as the wheel continues.

Low pressures or excessive loading exaggerate the amount of flex causing the sidewalls to bulge, but only as they rotate through that 10 degrees.
Hence the sidewalls are straight then bulging hundreds of times a minute causing the fiction/ heat then finally construction ply deterioration and bang!

 

[Skyliner33]

Another indication of too low pressure is if you check the tyre pressure when hot. If its increased a lot that indicates too low a cold pressure for pretty much the same reasons @Oldrat said.

 

[Ads_Essex]

Everyday is a school day

 

[Skyliner33]

Everyday is a school day

And conversely if your hot pressure is the same as cold then the tyre is overinflated so they don't flex much and generate any heat.. (Maybe applies to 2 wheel vehicles more than 4 but I cant see why)

 

[Oldrat]

Overinflated tyres make the sidewalls rigid and less prone to flex. It’s the flex that’s causes heat and leads to ply breakdown.
So little flex = little heat. (and reduces the contact area)

 

[elliot330]

Hi Bognormotors... T32 4motion here,

running 275/40/20's as supplied by Lieghton vans, Powertrac city racers tyres, 46psi. Lasted 7000 mile and completely worn out on the rear, evenly, half worn on the front.

Ref B14's being hard on the tyre? How can a lowered van be harder on tyres than a standard shocked van?

Thanks
Elliot

PS. Looking for new tyres, hence found this thread

 

[Fish]

245/35/20.
Air
47psi

 

[BognorMotors]

Hi Bognormotors... T32 4motion here,

running 275/40/20's as supplied by Lieghton vans, Powertrac city racers tyres, 46psi. Lasted 7000 mile and completely worn out on the rear, evenly, half worn on the front.

Ref B14's being hard on the tyre? How can a lowered van be harder on tyres than a standard shocked van?

Thanks
Elliot

PS. Looking for new tyres, hence found this thread

We are running 20” tyres in either 275/35 or 265/40 at anywhere between 36-40psi. The 275/40 is an oversize tyre. 46psi seems far too high. On our present 4-motion demo we are running 36 and this is what we recommending at present.

B14’s/arbs ask more of the tyres than the standard suspension. They tyres are working a lot harder, to keep the van stable and level, and provide a better ride. The rears seem to wear out quicker, even on the back of our old 2wd 300PS TSI, they lasted 7-8000 miles, this was at 40psi.

Remember as well, we are using softer SUV tyres on commercial vehicles which doesn’t help the life of them.

 

[Hah!]

I saw around the same mileage on same size tyre (275/35), 40mm lowered and running at about 40psi, went back to OEM 17" and got 18k miles...

 

[LT2019]

I’ll stick to my 18” if only getting 7k on 20s!

 

[Andyf]

Hi

Just a quick question
Got some after market alloys 20 inc tyres

What pressures are people running them at

Cheers
Andy