Alarming Tyre Wear on Michelin Pilot 4S 35is
- Thread starter baz-j
- Start date
Zforbes said:My mate with a 996 911 C4 runs his rears at 44 because Porsche recommend it in his owners manual
BMW have calculated what pressure your tyres run flat on the road (giving full road contact) based on diameter, width, profile and axle weight, I'm not clever enough to do the sums but I trust BMW are IMO so who am I to argue
The difference between 38 and 41 is not significant IMO.
I only recently sold my 997 Carrera4 so i'm well aware what pressures work :wink: ie
Summer and Winter tyres
17 inch and 18 inch wheels :-
Front 29 psi (2.0 bar)
Rear 36 psi (2.5 bar)
19 inch wheels :-
Front 32 psi (2.2 bar)
Rear 36 psi (2.5 bar)
These tyre pressures are valid only for Porsche approved tyres.
or
Tyre Pressure results for : Porsche 911
We have found 1 tyre size that matches your vehicle. Your tyre pressures are as follows :
FRONT TYRE SIZE FRONT TYRE PRESSURE REAR TYRE SIZE REAR TYRE PRESSURE
235/35/R19 Y 91 33 PSI / 2.3 BAR 295/30/R19 Y 100 36 PSI / 2.5 BAR Search for 235/35/R19 Y 91 on TyreShopper
Search for 295/30/R19 Y 100 on TyreShopper
etc etc
& implying that Bmw know best
yeah that's why 50% if not more of Z owners on this forum swap the recommended RFT for standard mr wilks said:Zforbes said:My mate with a 996 911 C4 runs his rears at 44 because Porsche recommend it in his owners manual
BMW have calculated what pressure your tyres run flat on the road (giving full road contact) based on diameter, width, profile and axle weight, I'm not clever enough to do the sums but I trust BMW are IMO so who am I to argue
The difference between 38 and 41 is not significant IMO.
I only recently sold my 997 Carrera4 so i'm well aware what pressures work :wink: ie
Summer and Winter tyres
17 inch and 18 inch wheels :-
Front 29 psi (2.0 bar)
Rear 36 psi (2.5 bar)
19 inch wheels :-
Front 32 psi (2.2 bar)
Rear 36 psi (2.5 bar)
These tyre pressures are valid only for Porsche approved tyres.
or
Tyre Pressure results for : Porsche 911
We have found 1 tyre size that matches your vehicle. Your tyre pressures are as follows :
FRONT TYRE SIZE FRONT TYRE PRESSURE REAR TYRE SIZE REAR TYRE PRESSURE
235/35/R19 Y 91 33 PSI / 2.3 BAR 295/30/R19 Y 100 36 PSI / 2.5 BAR Search for 235/35/R19 Y 91 on TyreShopper
Search for 295/30/R19 Y 100 on TyreShopper
etc etc
& implying that Bmw know best
flybobbie said:
Morris Ital - a Morris Marina by any other name
I know the road well
mr wilks said:mr wilks said:Zforbes said:My mate with a 996 911 C4 runs his rears at 44 because Porsche recommend it in his owners manual
BMW have calculated what pressure your tyres run flat on the road (giving full road contact) based on diameter, width, profile and axle weight, I'm not clever enough to do the sums but I trust BMW are IMO so who am I to argue
The difference between 38 and 41 is not significant IMO.
I only recently sold my 997 Carrera4 so i'm well aware what pressures work :wink: ie
Summer and Winter tyres
17 inch and 18 inch wheels :-
Front 29 psi (2.0 bar)
Rear 36 psi (2.5 bar)
19 inch wheels :-
Front 32 psi (2.2 bar)
Rear 36 psi (2.5 bar)
These tyre pressures are valid only for Porsche approved tyres.
or
Tyre Pressure results for : Porsche 911
We have found 1 tyre size that matches your vehicle. Your tyre pressures are as follows :
FRONT TYRE SIZE FRONT TYRE PRESSURE REAR TYRE SIZE REAR TYRE PRESSURE
235/35/R19 Y 91 33 PSI / 2.3 BAR 295/30/R19 Y 100 36 PSI / 2.5 BAR Search for 235/35/R19 Y 91 on TyreShopper
Search for 295/30/R19 Y 100 on TyreShopper
etc etc
& implying that Bmw know best
997 is a newer car than the 996 not for your benefit being a previous porsche owner, for other readers.
The 996 C4 runs 36 front 44 rear and listed just as a comparison to our zeds 41 rears.
Also, I didn't suggest RFT's are better at all, mine are going as soon as I burn them out, I think they are bloody awful. Most cars lost there spares due to weight removal quite a few years ago, BMW's solution was the RFT whilst other manufacturers chose tyre weld and inflator. Both options have their positives and negatives.
My point was BMW know best on what tyre pressure should be and maybe its 41 because the RFT's are fitted as standard and normal tyres should be different pressures.
So my question back, what are the benefits of running lower pressures?
Zforbes said:mr wilks said:mr wilks said:I only recently sold my 997 Carrera4 so i'm well aware what pressures work :wink: ie
Summer and Winter tyres
17 inch and 18 inch wheels :-
Front 29 psi (2.0 bar)
Rear 36 psi (2.5 bar)
19 inch wheels :-
Front 32 psi (2.2 bar)
Rear 36 psi (2.5 bar)
These tyre pressures are valid only for Porsche approved tyres.
or
Tyre Pressure results for : Porsche 911
We have found 1 tyre size that matches your vehicle. Your tyre pressures are as follows :
FRONT TYRE SIZE FRONT TYRE PRESSURE REAR TYRE SIZE REAR TYRE PRESSURE
235/35/R19 Y 91 33 PSI / 2.3 BAR 295/30/R19 Y 100 36 PSI / 2.5 BAR Search for 235/35/R19 Y 91 on TyreShopper
Search for 295/30/R19 Y 100 on TyreShopper
etc etc
& implying that Bmw know best
997 is a newer car than the 996 not for your benefit being a previous porsche owner, for other readers.
The 996 C4 runs 36 front 44 rear and listed just as a comparison to our zeds 41 rears.
Also, I didn't suggest RFT's are better at all, mine are going as soon as I burn them out, I think they are bloody awful. Most cars lost there spares due to weight removal quite a few years ago, BMW's solution was the RFT whilst other manufacturers chose tyre weld and inflator. Both options have their positives and negatives.
My point was BMW know best on what tyre pressure should be and maybe its 41 because the RFT's are fitted as standard and normal tyres should be different pressures.
So my question back, what are the benefits of running lower pressures?
Benefits from my own perspective are a less skittish & more compliant ride plus less likely to get impact damage to rim .
What i have gathered from my forum wheeling time is when it comes to wheel size , wheel fitment , tyre size , tyre brand & tyre pressures there just isn't a definitive answer to what is best in every aspect of the above , just way too many differentials .
Information shared is only a guidance but ultimately the driver / owner has to go with what they feel is best for them .
I do take issue when its suggested Bmw know best but you intend going against that theory by fitting non runflats :? they either do know best or they don't :wink:
mr wilks said:
Thanks for your thoughts, much appreciated and I will take your comments on board next time I pump my tyres up. Not wanting to start a disagreement, each to their own.
I have always gone with manufacturers guidance on pressures and never had a problem even when I drive with a heavy foot, if anything I've lost grip when pressures are down and not high. I believe people think because it sounds high to cars they've run in the past but they will be because low profile wide tyres do need more pressure to maintain contact on the road which does result in better grip and tyre wear evenness.
I don't agree with the rim damage though neither do I agree with causing wheels to crack even on RFT's. This is a common misconception because they are hard. The only impact RFT's have on wheel cracking is due to the amount of leverage pressure caused when fitting tyres due to the stiff bead. Cracking is caused by damage on the edge of the wheel that creates stress points that start the cracking.
What I'm saying is those running 326m and other prone wheels is keep your eye on the fitters and their tyre levers damaging the edge. If you do get a corner dent dress it out with a needle file to even out the stress propagation point. Not easy with a tyre on but doable if careful.
Also, I haven't said on any of my posts that RFT's are better. 2nd car I've purchased with them on, last one they got ditched and so will my zed when I've burnt them out.
[ref]Zforbes[/ref],
My point was BMW know best on what tyre pressure should be and maybe its 41 because the RFT's are fitted as standard and normal tyres should be different pressures.
So my question back, what are the benefits of running lower pressures?
In my experience the RFT’s with that pressure were just meh....... that how the run flats are. The PS4S’s with 41 felt they were running on a central band and definitely didn’t feel like the tyre was sitting flat on the road, dropped to 38, was better but nor perfect. Dropped to 34, too soft and didn’t feel great, back up to 36 and feels the best out of the lot.
Each time I adjusted the pressure I ran it up the same bit of road for comparison so they were being compared like for like before settling on 36. Fronts are running 34
My point was BMW know best on what tyre pressure should be and maybe its 41 because the RFT's are fitted as standard and normal tyres should be different pressures.
So my question back, what are the benefits of running lower pressures?
In my experience the RFT’s with that pressure were just meh....... that how the run flats are. The PS4S’s with 41 felt they were running on a central band and definitely didn’t feel like the tyre was sitting flat on the road, dropped to 38, was better but nor perfect. Dropped to 34, too soft and didn’t feel great, back up to 36 and feels the best out of the lot.
Each time I adjusted the pressure I ran it up the same bit of road for comparison so they were being compared like for like before settling on 36. Fronts are running 34
Not the only cause but I believe a common cause of a crack in a wheel that hasn't failed prematurely.
I visited a very large facility in Germany a few years ago for work and watched the manufacturering process for alloy wheels. Company was Otto Fuchs well known for their porsche alloys for those who don't recognise the name. It's an aluminium forging company that manufacturer parts for aerospace also which was the reason I was there but I won't bore you with that
Early failures are most definitely caused by hairline cracking on the outer edge of the ally billet used to make these things. The aerospace parts use fluorescent penetrant inspection detect this type of failure. The high volume auto industry doesn't as its too expensive.
If anyone is interested in how these are made I'd be happy to share knowledge as good as I can explain without trying to use engineering terminology that likely causes confusion.
I visited a very large facility in Germany a few years ago for work and watched the manufacturering process for alloy wheels. Company was Otto Fuchs well known for their porsche alloys for those who don't recognise the name. It's an aluminium forging company that manufacturer parts for aerospace also which was the reason I was there but I won't bore you with that
Early failures are most definitely caused by hairline cracking on the outer edge of the ally billet used to make these things. The aerospace parts use fluorescent penetrant inspection detect this type of failure. The high volume auto industry doesn't as its too expensive.
If anyone is interested in how these are made I'd be happy to share knowledge as good as I can explain without trying to use engineering terminology that likely causes confusion.
Argyll Andy said:[ref]Zforbes[/ref],
In my experience the RFT’s with that pressure were just meh....... that how the run flats are. The PS4S’s with 41 felt they were running on a central band and definitely didn’t feel like the tyre was sitting flat on the road, dropped to 38, was better but nor perfect. Dropped to 34, too soft and didn’t feel great, back up to 36 and feels the best out of the lot.
Each time I adjusted the pressure I ran it up the same bit of road for comparison so they were being compared like for like before settling on 36. Fronts are running 34
Thanks Andy, I watch a lot of F1, the tyres are preferred to run low pressure for a reason only to get the fastest times although there is far too much complexity for me to understand on albeit small rims and tyres that are not fit for general use but tyre temp and brake temp being a good reaon to do so, so not a good comparison IMO for road cars but there is probably more to it than I can understand.
TBH I dont mind, in fact a like a bit of rear end wiggle when giving full beans at lower speeds but I think tyre temp and hardness of rubber is more about grip than pressure and tyre tread. The Bridgestone RFT's might as well be made of concrete with the only other tyres ive had little grip with are Pirelli's, others rate them but I hate them, non RFT's with little grip, not sure how hard they are though.
Ive never rin the PS4's on any car so not in a position to comment
With non RFT's which I hope to run soon when I get it back and burn the old tyres I will experiment with pressures and report back, will certainly start at 41 on the rears though as wide low profile feels about right to me
Got the car back and took it straight to KwikFit to get two new shiny Pilots on the rear. BMW had checked the bushings and said they were ok. Looks like faster inner edge wear is standard given the camber on zeds (after the fact forum search...), but not too obvious to spot. As for the rips - I couldn't see them when laying flat on the ground with the tyres in situ so I'm bloody lucky to have taken it in for the suspension to be done for it to show up.
Having seen the old tyre removed from the car it's the case that the 4mm 'inner' measurement that the dealer gave at MOT was taken in a different location on the tyre to the 1mm measurement taken at the vehicle inspection last week. Hence the question mark over why there should be 3mm of wear with low mileage done since MOT - the answer is this wasn't the case...
At MOT they gave the depth of the innermost deep groove that wraps around the circumference of the tyre - which is what I'd expect. At the vehicle inspection last week in the same location on the report they entered the depth of the lateral sipes that form the pattern at the inner rim of the tyre as 1mm. The innermost groove going around the circumference was still 4mm deep.
I had KwikFit do an alignment check and the rears are spot on, but the fronts need doing. They wanted £79 just for the fronts, told them not today thanks as I wanted to get an opinion here on where to go.
I'm in Surbiton, SW London - PistonHeads had some posts saying Hounslow Tyres (£35 for fronts only) has a Hunter system that is operated by people who know what they are doing. Wheels in Motion is too far. Anyone used Tutts of Dorking, their website claims they have a pretty advanced system? (Hoffman rather than Hunter)
Any recommendations?
Having seen the old tyre removed from the car it's the case that the 4mm 'inner' measurement that the dealer gave at MOT was taken in a different location on the tyre to the 1mm measurement taken at the vehicle inspection last week. Hence the question mark over why there should be 3mm of wear with low mileage done since MOT - the answer is this wasn't the case...
At MOT they gave the depth of the innermost deep groove that wraps around the circumference of the tyre - which is what I'd expect. At the vehicle inspection last week in the same location on the report they entered the depth of the lateral sipes that form the pattern at the inner rim of the tyre as 1mm. The innermost groove going around the circumference was still 4mm deep.
I had KwikFit do an alignment check and the rears are spot on, but the fronts need doing. They wanted £79 just for the fronts, told them not today thanks as I wanted to get an opinion here on where to go.
I'm in Surbiton, SW London - PistonHeads had some posts saying Hounslow Tyres (£35 for fronts only) has a Hunter system that is operated by people who know what they are doing. Wheels in Motion is too far. Anyone used Tutts of Dorking, their website claims they have a pretty advanced system? (Hoffman rather than Hunter)
Any recommendations?
baz-j said:
I'd be surprised if that amount of tyre wear on the rears is normal and acceptable although I'm new(ish) to Z4 ownership so stand being corrected.
I'd say at some point your tyre pressure has been run low as in the 20's not 30's or 40's PSI. Like you've said it wasn't noticable until you were made aware of it. Not sure how the TPMS works on the E89 but if it's based on wheel speed sensors like older BMW's I've had then a slow reduction in pressure does not trigger the TPMS.
Should you get the front done?
Cars over time do settle and this could give you an amount of error that will show incorrect results but I'd be asking myself a few questions like,
Have I hit something hard enough to move the geometry? Have the tyres worn unevenly? is the steering wheel not centered when driving in a straight line? Does it handle like a bag of spanners? If all 4 answers are a no, personally I wouldn't be getting it done, I may be in the minority again though
Why is it out? KwikFit use the Hunter system and as far as I'm aware it's the most reliable system available but how well trained are the technicians? How reliable is the system in the first place and are they just trying to relieve you of your hard earned?
Did they give you the amount of error or do you have to pay for that?
Zforbes said:baz-j said:
I'd be surprised if that amount of tyre wear on the rears is normal and acceptable although I'm new(ish) to Z4 ownership so stand being corrected.
I'd say at some point your tyre pressure has been run low as in the 20's not 30's or 40's PSI. Like you've said it wasn't noticable until you were made aware of it. Not sure how the TPMS works on the E89 but if it's based on wheel speed sensors like older BMW's I've had then a slow reduction in pressure does not trigger the TPMS.
Should you get the front done?
Cars over time do settle and this could give you an amount of error that will show incorrect results but I'd be asking myself a few questions like,
Have I hit something hard enough to move the geometry? Have the tyres worn unevenly? is the steering wheel not centered when driving in a straight line? Does it handle like a bag of spanners? If all 4 answers are a no, personally I wouldn't be getting it done, I may be in the minority again though
Why is it out? KwikFit use the Hunter system and as far as I'm aware it's the most reliable system available but how well trained are the technicians? How reliable is the system in the first place and are they just trying to relieve you of your hard earned?
Did they give you the amount of error or do you have to pay for that?
I haven't had tracking done on the car since the original set of tyres were bought several years ago and I have had a few potholes in that time. The offside front was red at 0.00 degrees (ie no toe-in so out for sure) and the nearside I don't recall but enough to be red. The guys said it was biased to the right.
baz-j said:
Quick google check for the numbers (don't quote me)
Front:
Camber: -.1 to -1.1 degrees
Caster: 6.5 degrees (no range listed)
Toe: .02 deg to .22 deg
SAI: 14.2 deg
Included Angle: 13.6 deg
That toe setting is tight IMO, I'd go back and get it rechecked just to see how repeatable that result is, if it repeats then make that small adjustment, id also ask to check whilst I was sat in the drivers seat :evil:
I'll keep an eye on this as I'm interested on the outcome and others opinions
I think BMW say loaded when tracking is checked.
From manual:
"Vehicle with complete equipment for normal operation
with:
2 x 68 kg on front seats (seats in central position); 1 x 14
kg in luggage compartment (centre) and full fuel tank."
Front toe limit. Total toe-in 0° 14' ± 12'
Rear toe limit is more than front.Total toe-in 0° 18' ± 12'
From manual:
"Vehicle with complete equipment for normal operation
with:
2 x 68 kg on front seats (seats in central position); 1 x 14
kg in luggage compartment (centre) and full fuel tank."
Front toe limit. Total toe-in 0° 14' ± 12'
Rear toe limit is more than front.Total toe-in 0° 18' ± 12'