225/50-16 is a perfect fit on a 7" rim, and is a tolerable fit (just) on an 8" rim. Fitted on an 8" rim, they will probably wear at the edges first. Fitted at the rear, this will likely exacerbate the usual inner edge camber wear we all know and love..... Oh, and reduce grip, too.
245/45-16 is a perfect fit on an 8" rim. Overall diameter is 626mm, (cf 632 for the 225/50-16). This is a little smaller than is ideal, but it will probably mean that new 245/45-16s will be a decent match for front (worn) 225/50-16s. If you have odd diameter tyres this could upset the ABS (if fitted).
cheers
Under Car Knocking under hard first gear launch
Moderators: GRNSHRK, ron, bfons
In common with most people I only have sets of four alloys thus using a 240/45 x 415 as a spare. I've had to use that size spare alongside 225/60 x 15 and 235/45 x 17 with no upsetting of the abs; in fact the M6 runs 235/45x17 at the front with 255/40x17's at the back with again no abs upset - the only thing that upsets my abs is sheer age and speeds over 85mph on the 635.245/45-16 is a perfect fit on an 8" rim. Overall diameter is 626mm, (cf 632 for the 225/50-16). This is a little smaller than is ideal, but it will probably mean that new 245/45-16s will be a decent match for front (worn) 225/50-16s. If you have odd diameter tyres this could upset the ABS (if fitted).
Sharkfan
Hi Sharkfan,
if your ABS light comes on over 85mph, you probably have a failed sensor. You should look to get it fixed, anyway; once the light is on, you have no ABS at all, before that you probably have bad ABS which might be worse than useless.
Re you wheel sizes;
635:
Spare: 240/45 x 415 =631 nominal diameter
225/60 x 15 =652 diameter
235/45 x 17 =644 diameter
M6 :
235/45x17 =644 diameter
255/40x17 =636 diameter
These sizes are all actually close enough for it not to be a worry, except perhaps for the first two. Even then it might not matter with a single odd wheel that is smaller because;
a) The front wheels will be turning at different rates when cornering anyway, so it should require a relatively large difference in front wheel speeds to activate the ABS. Fitting a small spare the front of the car shouldn?t cause an ABS problem.
b) Some older 6ers had just one ABS sensor at the back, so didn?t individually measure rear wheel speeds. A single odd rear wheel (big or small) won?t throw it out too much.
c) A single small wheel will rotate faster than the other three. An ABS event should normally be triggered by a single wheel (or pair of wheels with some systems) going slower than the others, not faster.
Wheel size issues causing a dangerous inadvertent ABS intervention is most likely with a pair of larger wheels at the front, and small ones at the rear. If (say) you were to use 652 diameter fronts together with very worn tyres which had a nominal original diameter of 626mm (say) at the rear this could do it. The result might be that the front brakes (which normally do most of the work) would always be pulsing ?off? due to ABS intervention, and that you will not be able to stop properly. The other way round isn?t so bad; you can usually afford to lose the rear brakes.
To counter the possibility of ABS function interfering with normal braking, on cars where the spare wheel matches neither front nor rear perfectly for size (eg. compact spare on some cars with asymmetric fitments) it is recommended that you pull the ABS fuse or otherwise disable the system when using the spare wheel.
Cheers
if your ABS light comes on over 85mph, you probably have a failed sensor. You should look to get it fixed, anyway; once the light is on, you have no ABS at all, before that you probably have bad ABS which might be worse than useless.
Re you wheel sizes;
635:
Spare: 240/45 x 415 =631 nominal diameter
225/60 x 15 =652 diameter
235/45 x 17 =644 diameter
M6 :
235/45x17 =644 diameter
255/40x17 =636 diameter
These sizes are all actually close enough for it not to be a worry, except perhaps for the first two. Even then it might not matter with a single odd wheel that is smaller because;
a) The front wheels will be turning at different rates when cornering anyway, so it should require a relatively large difference in front wheel speeds to activate the ABS. Fitting a small spare the front of the car shouldn?t cause an ABS problem.
b) Some older 6ers had just one ABS sensor at the back, so didn?t individually measure rear wheel speeds. A single odd rear wheel (big or small) won?t throw it out too much.
c) A single small wheel will rotate faster than the other three. An ABS event should normally be triggered by a single wheel (or pair of wheels with some systems) going slower than the others, not faster.
Wheel size issues causing a dangerous inadvertent ABS intervention is most likely with a pair of larger wheels at the front, and small ones at the rear. If (say) you were to use 652 diameter fronts together with very worn tyres which had a nominal original diameter of 626mm (say) at the rear this could do it. The result might be that the front brakes (which normally do most of the work) would always be pulsing ?off? due to ABS intervention, and that you will not be able to stop properly. The other way round isn?t so bad; you can usually afford to lose the rear brakes.
To counter the possibility of ABS function interfering with normal braking, on cars where the spare wheel matches neither front nor rear perfectly for size (eg. compact spare on some cars with asymmetric fitments) it is recommended that you pull the ABS fuse or otherwise disable the system when using the spare wheel.
Cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ABS
Hi,
I was mmerely stating exactly what Ron said; the ABS system is remarkably tolerant of different wheel and tyre sizes. As for my own 85mph glitch, it hasn't worsened in 6 years so I suspect the crude on the rotor rather than the sensor - another one of those 'I'll get around to it' jobs :)
Sharkfan
I was mmerely stating exactly what Ron said; the ABS system is remarkably tolerant of different wheel and tyre sizes. As for my own 85mph glitch, it hasn't worsened in 6 years so I suspect the crude on the rotor rather than the sensor - another one of those 'I'll get around to it' jobs :)
Sharkfan