Tyre Pressure?

[hybrid 1044]

One things for sure, over inflating the tires or consistantly running high pressures places a lot of strain on the inner casing. Was shown recently how much of a hard life tires get and the effects of over heating and delamination of the inner casing. Was quite scary.

[kiwi535 538]

most low profile tyres (ie 215/45/17) have a average max pressure recommendation of 50psi but thats the manufacturers suggested limit for when seating the tyre when first fitted to the rim.

Recomended tyre pressure(as suggested by me a qualified tyre fitter )

235 45 17s 36 or 38psi

i reckon thats the low end for a 5 series

[edhardley 0]

34 psi on low profiles? say hello to impact fractures an quickly worn out tyres dude. 36 would be sticky enough al our customer run that no problems high pressure decreases the chance of side wall damage actually as well not sure bout steering feel thing tho. being rear drive you would want more grip in the rear less likely to spin out from loosing traction. as suggested 38 or 36 for best results. an punctures happen anytime anywhere as well nothing going to stop a nail or screw jamming itself into your tyre dude, but lower treaded(worn out) tyres more prone to punctures as there is a greater surface area contacting the road

I have a guy do my tyres whos been fitting tyres for the past 20 years, and see track e30's getting new rubber done at his mag n turbo ova the shore. What I said he reccomends, I'm guessing he knows what hes doing. It is common knowlege to have more pressure on back than front.. ur back tyres are your driving tyres, unless you want to reduce speed and acceleration you want them pumped well, ur front tyres are ur steering tyres(obviously) and they need controll so you want more tyre sticking to the road. (this is the same idea for staggered race wheels). Safety wise unless you go to either extreme(too pumep or to little), pressure will have little effect, the tyre itself is more important (get something for atleast $250 a trye or your comprimising alot). Im no tyre expert just repeating what somone with the knowlege reccomeneded me... and find it great. BTW worn out tyres (unless completely done- no tread in which case you wouldn't be driving) have the same surface area on the ground no matter how much tread they got left on them (the tread goes down perfectly perpendicular to the tyre).. If you painted your tyres tread at new, then rolled it along the ground, then after a year the footprint it leaves behind would be indentical...

[Apex Effects 3]

Well, BMW figures say 323i E36 F30-R36, and we run factory recommended F31-R37 in our E46.

But perhaps this is wrong, Is 215/45R17 a factory E36 size? There's only 225/45R17 in the list?

Note, I am not a qualified tyre person. Just wondering why BMW used such different figures to what you're recommending. Perhaps German roads are much different to ours (this is assuming they use universal pressures for all countries).

Our roads are alot rougher than german roads. also they quoting that pressure for the factory tyre a Michelin or Continental which in comparison to most of the stuff available(Bridgestone, Dunlop, Firestone) over here are alot softer compound. so higher pressures usualy preferable in my experience.

endors3series your mag an turbo guy has recommended what he thinks is best. its just my experience in the industry say what i've said an thats what my boss has told me to do so(dont argue with the boss he's had bout the 20 year mark in experience as well) so each to there own all i know is it works for me an the customers i serve. on the subject of tyre surface contacting the road it does vary just how the tyres have worn how your suspension is set up as well to much camber etc

[Apex Effects 3]

One things for sure, over inflating the tires or consistantly running high pressures places a lot of strain on the inner casing. Was shown recently how much of a hard life tires get and the effects of over heating and delamination of the inner casing. Was quite scary.

to higher pressure is never good for a tyre your quiet right, but pressure wise 36 to 40psi is safe running pressure for everyday use. depending on the compound of tyre an quality of its manufacturing is they key to what pressure to run along with size

no pressures are model of car dependent. its a general figure for that size tyre with the expected load that it can carry

[zenetti 0]

Well, BMW figures say 323i E36 F30-R36, and we run factory recommended F31-R37 in our E46.

But perhaps this is wrong, Is 215/45R17 a factory E36 size? There's only 225/45R17 in the list?

Note, I am not a qualified tyre person. Just wondering why BMW used such different figures to what you're recommending. Perhaps German roads are much different to ours (this is assuming they use universal pressures for all countries).

Were those figures specific to the 17" wheels or were they referring to a 15" or 16" tyre size? You will find that the lower the profile tyre generally the higher the recommended pressure rating.

A 225/45/17 is 100% the correct upsize tyre for most 3 series BMW, however on some BMW's (little baby 4 cylinders ) a 215/45/17 is fine as it is only 9mm smaller in overall diameter. this equates to 4.5mm top and bottom.

If you figure that new tyres usually have approx 8mm of tread and have 6.5mm of usuuble tread before they need to be replaced the 4.5mm difference is less than the difference between a new tyre and a tyre that needs to be replaced. ( hope that makes sense).

To ensure that your ABS works properly, gearbox works smoothly, speedo reads correct etc you should always try and keep within 3% of the original overall diameter when upsizing to new wheels and tyres.

Underinflated tyres are the most coommon cause of problems we see at work, and most customers assume that their owners manual is the bible. Generally the pressures listed in the manual are referring to the OE size tyre (generally a 15" or 16" tyre) and does not take into + sizing.

There is no magic formula for getting the pressures correct as every tyre manufacturer is different in terms of their construction, tread design, etc which is why there is ageneral recommendation pressure range.

You will also find that the better quality tyres have a much stronger sidewall construction and so do not need to run as high pressure as the cheaper ones. This has the flow on effect of giving the feeling of 'better grip'. You will find by adding extra psi you are artificially strenghtening the sidewall of the tyre, which is needed in the cheaper tyres.

It always pays to check the construction of the tyre, as I think this far more important. This is generally in very small print in the sidewall of the tyre. I won't go into explaining that here as well as that will require the writing of another novel

At the end of the day it pays to talk to the person that is selling you tyres to get the correct info. If you don't feel comfortable with their knowledge ( or lack of) buy your tyres somewhere else.

[greenday-rulz21 6]

So Jono, what do you recommend for 215/45 17's on a 7.5 rim?

Fronts are Toyo Proxes, Rear, Bridgestone Potenza's.

[zenetti 0]

GASTKR was pretty much spot on with his thoughts. I would run 36psi and go up to 38psi if it feels a bit soft

[Creaver 55]

And what about for my e34 540i?

Fr - 235/45R17 something called Lutons

Rear - 255/40/17 Nankang sport

[Apex Effects 3]

And what about for my e34 540i?

Fr - 235/45R17 something called Lutons

Rear - 255/40/17 Nankang sport

eeee Lutons (flavour of the month Chinese crud) id look at upgrading them if ya can afford it dude. they cheap an very prone to impact fracturing an cracking in the sidewall from poor manufacturing. but if ya stuck with them 38 front 36 rear or 38 all around. well that's my recommendation change to suit your ride comfort level.

[zenetti 0]

eeee Lutons (flavour of the month Chinese crud) id look at upgrading them if ya can afford it dude. they cheap an very prone to impact fracturing an cracking in the sidewall from poor manufacturing. but if ya stuck with them 38 front 36 rear or 38 all around. well that's my recommendation change to suit your ride comfort level.

bang on the money again . I would run 38psi all round, just cos Nankang's aren't exactly a 'quality' brand. (No offence intended).

[Creaver 55]

They came with the rims, definitely on the to-do list. Thanks for the advice

[zenetti 0]

Agreed 3 pedals - you mentioned suspension, which I forgot all about.

Suspension also has a huge effect on your tyres, if your suspension is worn out it will cause detrimental wear to your tyres.

[Creaver 55]

Thanks Johno and 3pedals for the info.

[westy 614]

Jeez you guys run big pressures!

I usually run around 32-34 psi!

[westy 614]

But that is open road and twisty including a little gravel.

I used 40 PSi at Taupo and it was great on the track, but out on the road it was intolerantly hard and handled like a roller skate! These were 235/40/17 Toyo T1r too.

The car is set up differently from most mind.

Different strokes for different folks I guess.

[Asi 0]

Please can someone tell me the correct tyre pressure for 215 45 r17 tyre size?

[B.M.W Ltd 950]

42 minutes ago, Asi said:

Please can someone tell me the correct tyre pressure for 215 45 r17 tyre size?

Round town/daily I would run 33 PSI

[KillerX 40]

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