Author Topic: Optimum tyre pressure  (Read 1573 times)

AlexS

  • Approved Member
  • *
  • Posts: 57
  • Country: gb
  • My Honda: HONDA JAZZ 1.3 I-VTEC S 5-DOOR 2017.
Optimum tyre pressure
« on: February 15, 2023, 02:50:52 PM »
The max number of people I have in the car is 2. I have the pressure set to 30 with Cross Climate tyres..reckon that is OK? See pic.

I'm in the UK, all weather's, same old potholes. 1-3 hours travel per day.

Thanks...
« Last Edit: February 15, 2023, 02:52:57 PM by AlexS »
2017 HONDA JAZZ 1.3 I-VTEC S 5-DOOR - Orange Sunset II

AlexS

  • Topic Starter
  • Approved Member
  • *
  • Posts: 57
  • Country: gb
  • My Honda: HONDA JAZZ 1.3 I-VTEC S 5-DOOR 2017.
Re: Optimum tyre pressure
« Reply #1 on: February 15, 2023, 02:51:32 PM »
Delete this additional post. Sorry.
2017 HONDA JAZZ 1.3 I-VTEC S 5-DOOR - Orange Sunset II

ColinB

  • Approved Member
  • *
  • Posts: 1162
  • Country: gb
  • My Honda: 2015 Jazz 1.3 SE manual in Milano Red
Re: Optimum tyre pressure
« Reply #2 on: February 15, 2023, 03:38:21 PM »
The max number of people I have in the car is 2. I have the pressure set to 30 with Cross Climate tyres..reckon that is OK? See pic.

I'm in the UK, all weather's, same old potholes. 1-3 hours travel per day.

Thanks...

I have Crossclimate 2s on my car and I use the pressures on the placard, I'm not aware of anything from Michelin recommending lower pressures. Why would you run with the pressures less than the recommended? Is there some benefit in doing that? If not, then why not use what Honda recommend?

AlexS

  • Topic Starter
  • Approved Member
  • *
  • Posts: 57
  • Country: gb
  • My Honda: HONDA JAZZ 1.3 I-VTEC S 5-DOOR 2017.
Re: Optimum tyre pressure
« Reply #3 on: February 15, 2023, 03:57:27 PM »
The max number of people I have in the car is 2. I have the pressure set to 30 with Cross Climate tyres..reckon that is OK? See pic.

I'm in the UK, all weather's, same old potholes. 1-3 hours travel per day.

Thanks...

I have Crossclimate 2s on my car and I use the pressures on the placard, I'm not aware of anything from Michelin recommending lower pressures. Why would you run with the pressures less than the recommended? Is there some benefit in doing that? If not, then why not use what Honda recommend?

Look at the image I supplied. One shows a trailer, the other shows a full car of people and baggage. As stated the max number of passengers I have in the car is two (at the front). Maybe I should increase the tyre pressure for the front tyres.
2017 HONDA JAZZ 1.3 I-VTEC S 5-DOOR - Orange Sunset II

ColinB

  • Approved Member
  • *
  • Posts: 1162
  • Country: gb
  • My Honda: 2015 Jazz 1.3 SE manual in Milano Red
Re: Optimum tyre pressure
« Reply #4 on: February 15, 2023, 04:31:53 PM »
OK, I see where you're coming from now, sorry missed that subtlety in your original post. Your logic is that you normally run with a lighter load so you can have lower tyre pressures.

My reading of the placard is that those are Honda's recommended pressures. I believe some manufacturers do have different recommendations on their placards for lighter loads, but Honda have not done this for the Jazz. My personal view is that I'm not about to attempt to second-guess the engineers and do anything other than what they recommend. I've run the car like that from new (also mainly with one or two people only) and when I replaced the original tyres at 7 years and 38k miles they'd all worn pretty evenly, so there's nothing wrong with doing that. I can't see the benefit of what you're doing, and there are definite risks in running with under-inflated tyres.

Lord Voltermore

  • Approved Member
  • *
  • Posts: 1928
  • Country: gb
  • My Honda: 2021 Jazz EX
Re: Optimum tyre pressure
« Reply #5 on: February 15, 2023, 05:54:06 PM »
My standard' ex on 185/55/R16  tyres door label shows  35 psi front and 33 psi rears  for 3 persons.  (no lower alternative )

In years gone by  some makers showed a lower pressure  as normal  with a  higher pressure for high speed  use.    For  a few years one or two showed a lowe r'comfort'  pressure if you value a slightly softer ride over optimum economy /eco . 

Now tyres and car suspensions are designed for higher  pressure.  This gives better fuel economy.   Its also the pressure at which the cars  fuel consumption and emissions   were officially rated.   I dont think makers can now  recommend a lower pressure than this.  Even if it were safe, and we dont know it is.

I dont think its wise to  run at a significantly lower pressure than the recommended one.30 psi is probably too low.    It will increase fuel consumption  by a noticeable amount  and may have an adverse effect on handling and how the tyre behaves. They could overheat or wear prematurely. 
And many pressure gauges  are inaccurate.  The real pressure may be even less than you thought.
 
« Last Edit: February 15, 2023, 05:57:48 PM by Lord Voltermore »
  Trust a dog to guard your house  , but not your sandwich

Downsizer

  • Approved Member
  • *
  • Posts: 853
  • Country: gb
  • My Honda: Jazz 1.3 SE cvt - Feb '16 - Blue
Re: Optimum tyre pressure
« Reply #6 on: February 15, 2023, 06:08:50 PM »
The car weighs about 1100 kg and 2 passengers in the front might weigh another 140 kg, positioned midway between front and rear wheels. I see no reason to alter the recommended pressures.

TnTkr

  • Approved Member
  • *
  • Posts: 650
  • Country: fi
  • My Honda: 2019 GK5 Jazz 1.5 Dynamic 6MT
Re: Optimum tyre pressure
« Reply #7 on: February 15, 2023, 10:01:35 PM »
It is never advisable to use lower pressure than stated in user manual or sticker. What are the pressures stated in manual?

Lower pressure has negative effect on handling and rolling resistance, and makes tyres more prone to damage when hitting a pothole.

I usually fill up to 3-7 % higher pressure, than stated by manufacturer.

dvhttn

  • Approved Member
  • *
  • Posts: 51
  • Country: england
  • My Honda: Jazz Mk3 Ex CVT
Re: Optimum tyre pressure
« Reply #8 on: February 16, 2023, 09:54:19 AM »
The max number of people I have in the car is 2. I have the pressure set to 30 with Cross Climate tyres..reckon that is OK? See pic.

I'm in the UK, all weather's, same old potholes. 1-3 hours travel per day.

From Pirelli: "... Most manufacturers do not state a minimum tyre pressure, per se. The recommended value is the amount of air that a tyre needs for a car to handle properly and safely, and anything under that value is not recommended,  ..."  (From here - https://www.pirelli.com/tyres/en-gb/car/driving-and-tyre-tips/how-to-read/recommended-tyre-pressure    ).

Personally I regard the door jamb values as a minimum. Sometimes they are fine (when spread over several makes/models of cars and tyres!) but sometimes I find better handling/behaviour from slightly higher pressures. Everyone/every car/every tyre is different.
Dave
Carpe diem …

orangeTomato

  • Approved Member
  • *
  • Posts: 19
  • My Honda: MK3 Jazz
Re: Optimum tyre pressure
« Reply #9 on: February 19, 2023, 10:13:15 AM »
I'm running 36 PSI all around, which is above specification for my 15" wheels (31 PSI),

I'd agree about the fuel economy win. For my commute I reckon the difference is 7-10%  (extra-urban, 20 miles over 35 minutes, obsessively following the green/blue eco-nanny on the dash)

But that's probably different to a typical jazz driving environment. For mostly short journeys in town or stop/start traffic, fuel economy will be dominated by engine warmup and traffic conditions, so you wouldn't care about tyre pressure.

IMO it rides a bit louder than specification pressure, but the MK3 jazz is loud anyway. It doesn't make much difference.

Also feel a bit more transmitted vibration into the chassis, but it's not very significant, and as above the jazz isn't a very refined car in the first place.

« Last Edit: February 19, 2023, 10:20:05 AM by orangeTomato »

Kremmen

  • Approved Member
  • *
  • Posts: 4575
  • Country: england
  • Civinfo interloper
  • Fuel economy:
  • My Honda: MY22 Jazz EX
Re: Optimum tyre pressure
« Reply #10 on: February 19, 2023, 10:33:21 AM »
From Bridgestone :

Quote
Under inflated tyres

Driving on tyres that are underinflated is not just negligence, it is also very dangerous, being one of the leading causes of tyre failure. When tyre pressure is low, its surface area that touches the road increases. The increased footprint, if left unattended, will increase friction, which can cause overheating. Overheating, in turn, can lead to premature wear, tread separation, and eventually, a blowout. Depending on the severity of the blowout, you could lose control of the vehicle, putting you and other drivers in harm’s way.

The change in the footprint of the tyre also has other repercussions such as longer braking distances which can prove dangerous, and an increase in fuel consumption as more energy is needed to make the tyre roll.

Overinflated tyres

When it comes to tyres and air, there’s also the ‘too much of a good thing’ factor. In overinflated tyres, the sidewalls and tread become harder than normal and the contact patch of the tyre on the road shrinks. This change in footprint can reduce traction and performance, giving you a bouncy ride and affecting the handling of the car. Over-inflation will also cause uneven wear thereby decreasing the life of your tyres.
Let's be careful out there !

Jocko

  • Approved Member
  • *
  • Posts: 9356
  • Country: scotland
  • Fuel economy:
  • My Honda: Died from rust.
Re: Optimum tyre pressure
« Reply #11 on: February 19, 2023, 11:40:43 AM »
But there is overinflation and overinflation. I know of Hypermilers that raise their tyre pressures to the maximum pressure moulded into the tyre wall. To me, this is dangerous. However, I do not consider a 10% increase in pressure extreme and from my experience of doing just that, not detrimental to the wear on the tyre.

TnTkr

  • Approved Member
  • *
  • Posts: 650
  • Country: fi
  • My Honda: 2019 GK5 Jazz 1.5 Dynamic 6MT
Re: Optimum tyre pressure
« Reply #12 on: February 20, 2023, 03:39:23 PM »
By experience I can tell that inflating tyres remarkably over adviced pressure improves cornering and reduces tyre wear when driving fast e.g. on track, but may also reduce the lifetime on suspension bushings.

Tags:
 

anything
Back to top