11-04-2012, 06:08 AM | #1 |
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Tyre Pressure..
Hey guys it says in the manual for the 19's to have a tyre pressure of
32 for fronts and 35 for rear.. is this the optimum ?? I usually go 2 PSI more personally.. what do you guys go with |
11-04-2012, 06:21 AM | #3 |
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Serious??? That's strange as the front and rear are different..and we really shouldn't be over inflating.
Thanks for that CrazyLatte.. Anyone else got feedback? |
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11-04-2012, 01:48 PM | #6 |
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It really comes down to personal preferences.
Stillwell filled my tyres to 35psi all around. So I enjoyed the drive at those pressures for the first tankful. When I filled the car with petrol last, I increased the pressure to 37psi all around. I can't really tell if there is a difference yet. Both pressures seem to be very acceptable. I will go for 38psi next time and then maybe cycle down to 35psi to test a big change. I was filling the E90's 17" mixed tyres with around 36-38psi and all was good.
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11-04-2012, 01:49 PM | #7 |
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Silly thing double posted.
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11-05-2012, 02:44 AM | #10 |
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tyres compounds and tyre pressures are very important to me. Runflats are more of a grey area for me but i normally run +8-+10 psi from the recommended on my ultra high performance non runflat tyres. On the runflat tyres, i am running 36 psi front and 38 rear. when i upped them to 38 front and 40 rear, i was seeing less surface area of the tyre on the road
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11-05-2012, 03:09 AM | #11 |
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I thought of going 2 up from the recommended ie. 34 Fronts and 37 Rear..
How's the comfort factor when running 36 and 38 Sephanite? Spikey: Ya 39 for rears.. 36 for fronts.. I'm thinking if 39 is too high as summer is coming |
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11-05-2012, 03:46 AM | #12 |
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comfort factor? not hard enough i am on the standard suspension and its still very smooth. Keep in mind, if you do think its starting to feel bumpy, by just changing out of the rft's, the ride becomes a lot more smooth.
Just as a reference from my previous tyres: Bridgestone RE050a RFT: 36 all round Bridgestone RE040: 38 front 40 rear Pirelli p-zero nero: 40 front 42 rear Kumho Ku31: 38 front 40 rear Toyo R888 (semi): 28 front 30 rear goodyear Eagle F1 (non asymmetric version): 40 front 42 rear toyo T1R: 36 front 38 rear these are what i use to run in the different tyres i had. They are my personal preferences only to show you that there is no one tyre pressure. If you are not looking at fiddling around, garages normally pump to tyres to 36 and call it a day. Most of the time i do the same when people ask me to check their pressures |
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11-05-2012, 04:36 AM | #13 |
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As the last post picture says , tyrepressure is all about load, speed , and camber-angle( alignment) .
I once got hold of the European formula to calculate it, and went running with it. Came to know by surfing the net, that this formula is adequate for standard load and XL tyres, but the in America used power in this universal formula gives to low pressures, before 2005 ( then they swiched over to the European power in it, only for SL and XL), and there are many old lists hanging around on the net. Another thing is that you probably have low aspect ratio tyres ( the 40 in fi 235/40ZR18) for wich the maximum load of those tyres, is calculated to high by the tyre-makers. This has to be compensated, by using higher pressure. Calculated it rougly to be 25% more then the calculations would give. Comfort and gripp are totally gone then , but this is only for the savety of the tyres. Taking this all into account, you still can use a lower pressure when you are not fully loaded, the advice-pressure given on the doorstyle or somewhere else on the car, is for fully loaded ( then rear more weight then front) and maximum speed of the car. Higher when towing goes from the idea that then the Gross axle weight rating ( GAWR) rear is exeded often, wich is not allowed but happens in practice. Front axle seldomly gets overloaded. Goal of all the calculations is to keep the deflection of the tyre the same as when maximum load and reference-pressure on it ( wich is lower then the maximum pressure, depends on the tyre-type) So give me the data of your tyres like maximum load and tyre-kind ( Standard load or XL/Extraload/reinforced, all on the sidewall) and the GAWR's of the car. Also the exact sises for the AR ( aspect/ratio) Then I will give you a balanced advice for fully loaded. If you can produce a Empty weight and configuration of the car ( motor in front or back and front or back drive , number of seats ) and how you normally use it, I can give a more balanced advice for normal use. You may also try it yourselfes with use of spreadsheets on my skydrive. https://skydrive.live.com/?cid=a526e...E092E6DC%21128 But they are older spreadsheets in wich I did not work out the latest developments yet. So partly I have to do it by hand. This advice can then be used by others with the same model. Greatings from Holland Peter |
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11-05-2012, 07:21 PM | #14 |
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I did not know it was that complicated OMG! To not complicate things, it's usually just me and the mrs in the car we dont have any kids. So just going by the sticker psi should do fine?
This is what it says in the manual for speeds up to 120kmh Tire size Pressure specifications in bar/PSI for the 328 F: 225/40 R 19 89 Y RSC - 32 PSI R: 255/35 R 19 92 Y RSC - 35 PSI |
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11-06-2012, 02:45 AM | #16 |
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Just went to get my tires checked and funny thing I had pressures all over the place from 32 in the fronts to 44's and 40 in the rears.
The ride feels alot better now IMO i've got 35 fronts and 38's rears |
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11-07-2012, 01:40 PM | #17 |
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Let me first say that , thoug I gathered a lot information about tyres and tyre-pressure , I am not a tyre-specialist. I got interested in it when I had a camper, as we call it in Holland, RV is the name in America and probably also downunder,
So the RSC in the tires of J1n , I dont know what they mean. J1n try to find on the sidewalls the term reinforced/Extraload/XL, if so it is such a tyre with referencepressure(Pr) of 41 psi, otherwise its a normal car tire with Pr of 35 psi. this is needed for the calculation, so I dont calculate to low. The 120km/h a somewhat strange speed to give. Reference-speed for most tires is 160 km/99m/h but for Y speedrated tires it is 220km/h, but mayby this relatively low speed is used to compensate the to high calculated maximum load by the tyre-maker. Then I want to know what pressure and loadkinds are used in Australia. I think Kg and psi and km/h and degrees fahrenheit, so correct me when I am wrong. Also I need your GAWR's , In Europe they are on the VIN-plate , a metalish plate mostly in one of the doorstiles or under the motor-hood. In America they are on the same plate as the advice-pressures. I dont know where they are downunder, mayby downunder somewhere |
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11-10-2012, 01:56 AM | #18 |
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Thanks for trying to help jadatis..
I've been observing the wear after changing the pressure to 35 fronts and 38's rears. It's alot more grippy now which is good, rides alot better. As for the wear of the tire , seems there's a more even wear now on the front tires, but the rear wear seems abit too far from the side of the tires. I think this is because we do not drive with passengers 90% of the time. May consider reducing the rear pressure by 1-2. Last edited by J1n; 11-10-2012 at 06:20 PM.. |
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11-10-2012, 02:35 PM | #19 |
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When you are driving only with driver and co-driver and a little load, the load is moslty front and back the same, so the pressure can be the same front and rear.
So 35 all around would not be bad. In Europe before 2000, an advice was give for normal use, wich was meath for 3 persons and a little load, and was front higher pressure then rear even. After 2000 this normal use advice was not given anymore. But for this you have to calculate and need the empty weight and motor in front or back for estimating the division between front and back. |
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07-11-2013, 09:30 AM | #20 |
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Right, so question.
Have just had my F30 returned to me from Bridgestone from having a replacement rim put on it and noticed that the ride was alot harsher.. on checking the Psi it was running at 42 at the rears and 40 at the front. 225/45/18R/91Y Continental Contact Sport5 RFT The tyre pressures stated on the door card says 200 (29psi) front and 220 (32psi) rear... does anyone else think this is rather low?
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07-11-2013, 04:16 PM | #21 |
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I have always had 38 front and back on all my cars.
Having ridden (and still riding) motorcycles for a long time I have always been a bit pedantic when it comes to pressures. I check them once a week and always when the tyres are cold and NEVER rely on the gauge up the pump to be accurate. Spend a few bucks and buy your own pressure gauge and leave it in the boot/glove box! You would be surprised how inaccurate the servo gauges are. I have seen them out up to 10 PSI! As has been mentioned in a prior post, it is somewhat up to personal preference though. As long as you are around 36 - 40 you will be fine. Be safe. H |
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07-11-2013, 09:39 PM | #22 | |
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