Tyre Pressure

[HOSTILE]

So, as the topic suggests, I recently had a 19 inch 265/30 tyre with approx 4000 km of driving suffer a collapsed inner sidewall. The manufacturer says it was due to under inflation. I normally run around 34psi and have been told it should be 40psi. I've run that pressure for years with no trouble. What do you guys reckon? Discuss..

[Tommy Kaira RL]

I have always ran 32-34 psi in my tyres. Even on the track day I ran 32 psi to cope with the extra heat.If I put 40psi in tyres it seems to harsh of a ride. I've never had a blow out but I have seen tyres on other cars start to get big bubbles in the side wall before. I think it was a defect in the tyre that I saw.

I told one of the owners to take it back to where she got it from and they basically said the same thing it didn't have the right pressure.

It seems to be a cop out from the tyre retailers.

Is it possible to get a leak past the rim with hard take offs and cause the tyre to go down quick and blow it out?

Waits for derderpumkin to put his 1c worth into this thread.

[discoPumpkin]

just do what they recommend and u won't have any troubles, if u want to runner lower pressures for more grip on the track, perhaps change tyre manufacturers

[jrm]

34PSI sounds incredibly low to me - what you'd expect on a 185/60R14 or something.

When I get new tyres fitted, I always ask the staff what pressures to put in. Typically the lower the sidewall, the higher the pressures they're recommending. 40PSI sounds pretty normal for a 265/30 to me.

[Murry33]

i have 275/35/19s and run 38-40psi, no problems at all.

[Sinista32]

255/35/18 @ 40psi road use

[HOSTILE]

I have run same pressure on an 18 inch 265/40 on my old GTR for 6 years including 7 or 8 track days etc and never had any issue. If 40 psi is suggested and I run 34 that means its around 85% inflated. Is it reasonable to say that 15% under inflation will cause tyre failure??

I reckon thats a bit of a cop out. I was never instructed anything regarding pressure when getting these tyres. Surely they should come with a warning at point of purchase if this is so?

Anyway the tyre company has replaced the failed tyre but be careful guys!

[discoPumpkin]

who was the manufacturer anyway?

[D_Stirls]

The lower the profile the higher the pressure, for a 30 profile tyre 40psi is about right

[Murry33]

[discoPumpkin]

^I lold, then started dancing to it, then I checked my tire pressures, in that order

kind of weird I know

[Brandon]

The only time I've dropped the pressure to 34 was for a drag day once. Straight after that I've pump it back up to 38. I find 40 a bit too high personally and typically just run 38. 35-36 will give a slightly better grip but for daily driving 38 is good enough for me. 265/35/18 Michelin PS2.

[ISC-Performance]

34-38 I would have thought. The correct pressure range will be on the side of the tyre though!

[savage GTR]

I used to run 34psi in my 225;50;16 on my R32GTR but was told to low , told 40-44psi was better suited to my car .tyres were

K102 hankooks

Dunlop sp sport fast response

both above size and never had any problems like blow outs etc

[Krishy]

I run a 235/45/17 and the tyre shop guys recommend it be on 34psi. I normally bump it up to about 38-40 as I find this is gives me a better ride. Never had any issues at all.

If the manufacturer is saying that the issue is caused by under inflation than to me that is a massive cop out.

[34GeeTeeTee]

I run a 235/45/17 and the tyre shop guys recommend it be on 34psi. I normally bump it up to about 38-40 as I find this is gives me a better ride. Never had any issues at all.

If the manufacturer is saying that the issue is caused by under inflation than to me that is a massive cop out.

That would be my thoughts.... Unless it was running 20-30psi or something way out of spec!

[SLED]

Martin, get a few opinions from other Tyre joints.......34psi is hardly under inflated I would've thought.

What is the max reading on the sidewall?

[Nightcrawler]

Interestingly when I checked my rear 265/35/18 tyre pressures at Caltex Bolivar on the way to Kadina they were 44psi - I even commented on this to others there. I had them fitted around 2 months ago and had not checked them since.

Bizarrely the front 235/45/18s that were fitted by the same shop at the same time were 28 and 32psi - weird.

[gilly-R33]

yea i run the same as krishy.

I run a 235/45/17 and the tyre shop guys recommend it be on 34psi. I normally bump it up to about 38-40 as I find this is gives me a better ride. Never had any issues at all.

If the manufacturer is saying that the issue is caused by under inflation than to me that is a massive cop out.

[Race__24]

I run around 40-42 psi on my 18s depending on how the tyre is wearing. I would class 34 as under inflated on a tyre with such a small sidewall. The smaller the sidewall the higher the pressure you need. Roughly speaking, if you have half the sidewall with the same amount of flex it will get twice as hot.

It is also a good idea to check your pressures regularly, particularly after you have new tyres fitted. You will find that in the first 500km or so they will drop pressure as they bed in. I have had tyres drop 10 psi in the first week and then not drop again for 10,000k

Edited June 19, 2013 by Race__24