Road noise

[John Ratsey]

Not an easy job to put 15inch on the ex as the ex has tyre deflation warning which works on the rolling radius.
As I said before I have the ex with Bridgestone tyres and I have a lovely quiet ride.

My understanding from reading the Mk 3 handbook is that the deflation warning system works by comparing the rotational speed of the four wheels. There is also a recalibration facility to be used after changing a tyre or adjusting tyre pressures (which could change individual wheel's roation speeds relative to the average).

My interpretation is therefore that it would be possible to change between 16" and 15" wheels.

[Paulwhitt20]

Am I missing something, but isn't the tyre and wheel diameter for a 16" wheel the same as a 15" wheel when you include the size of the tyre as well. Otherwise the car would be a different height off the road. In which case the rotational speeds and rolling radius would be the same.

[guest5643]

Am I missing something, but isn't the tyre and wheel diameter for a 16" wheel the same as a 15" wheel when you include the size of the tyre as well. Otherwise the car would be a different height off the road. In which case the rotational speeds and rolling radius would be the same.

I think this is correct

[guest5664]

the sensor is fitted to the wheel and not to the tyre, so if you have a smaller radius wheel the sensor will be closer to the center of the wheel, so the speed of the sensor will be lower.

[guest5679]

I think the theory is that lower profile tyres are supposed to give better handling characteristics as the smaller sidewalls flex less. That would be good if you drive a racing car but for normal on the road driving I prefer the less harsh ride of a higher profile. Also there is the aesthetics - bigger wheels are seen as more up to date and trendy.

Sounds to me that I ought to test drive a Mk3 SE Jazz.  My local Honda dealer has only an EX with CVT demonstrator, but they have other branches in the area that might have an SE with CVT.

I have a very functional view of cars.  Top priorities for me are reliability, economy, comfort, quietness and practicality.  Cosmetics and aesthetics are very much lower considerations.

[Paulwhitt20]

I have a very functional view of cars.  Top priorities for me are reliability, economy, comfort, quietness and practicality.  Cosmetics and aesthetics are very much lower considerations.
[/quote]

Sounds like a Jazz then....

[guest5679]

Sounds like a Jazz then....

That's probably the nub of my problem!  Where do I look for an alternative?

Our Mk1 Jazz has been a brilliant car for 11 years but it is now showing its age (although still going strong!).  It has transported our two daughters and their belongings to and from university more times than I care to remember.  I never fail to be amazed at how much it can carry.  Would you believe that it has transported a floor standing, under the kitchen worktop size fridge, freezer and tumble dryer (not all at once, of course!)?

I'll probably end up buying the Mk3 Jazz.  But, first, I have to get over the psychological barrier of being disappointed with certain aspects of the Mk3 compared to the Mk1.

[guest5643]

Better the Devil you know 

[guest4324]

the sensor is fitted to the wheel and not to the tyre, so if you have a smaller radius wheel the sensor will be closer to the center of the wheel, so the speed of the sensor will be lower.

This would be correct if you were driving without tyres! However, a 15" wheel has a higher profile tyre than a 16" wheel, so it is irrelevant whereabouts the sensor is, the wheels will rotate at exactly the same speed because the total diameter ( wheel plus tyres) is the same.

[guest5664]

the sensor is fitted to the wheel and not to the tyre, so if you have a smaller radius wheel the sensor will be closer to the center of the wheel, so the speed of the sensor will be lower.

This would be correct if you were driving without tyres! However, a 15" wheel has a higher profile tyre than a 16" wheel, so it is irrelevant whereabouts the sensor is, the wheels will rotate at exactly the same speed because the total diameter ( wheel plus tyres) is the same.

the distance that the sensor makes in one turn of the wheel+tyre is less how closer it is to the centre.
less distance at the same time=lower speed
it makes the same amount of turns, but every turn he moves makes less distance.
imagine a wheel with 1meter diameter, and put the sensor at 2cm from the center, and later put the sensor at 90cm from the center, in witch case the sensor will be faster if the wheel +tyre are rolling at the same speed in both of the cases?

[culzean]

Stupot is correct,  the outside diameter of a 15" rim fitted with a 65 profile tyre is exactly the same as a 16" rim with a 55 profile tyre. This means revolution speed of the wheels as seen by the ABS sensor are exactly the same.  The ABS sensors do not move position, they take their pulses off the bearing on the axle of the wheel.

The tyre deflation warning is pretty sensitive as I have to reset mine when I get new tyres of exactly same make and size fitted on one axle (normally front tyres as they wear our quicker),  it you have 4 new tyres fitted the system will accept all wheels are now same diameter.