Been Said Before New Tyres Now Dash Lights On

[travman t sport]

i went and got two new tyres then the hand brake light , trc , vcs , abs lights all came on crapped my pants thought the worse. my own fault tho i wanted low pro so had 205/45/16 but could not afford all four so the back remaind the same 205/55/16 . when i went to the toyota garage to make sure it had nothing to do with brakes and they told me it didnt but said having 205/45/16 was dangerous and would effect the handling for the worst and could mess the abs up is this true . if i put the same size 205/45/16 on the back would that sort the problems ? any help would be good rant over

[shazzbaa]

ABS etc. compares wheel speeds and if there is a difference between front and rear

(and possibly left to right) it takes the relavent action , different size tyres will cause confusion .

Even small differences in tyre sizes can upset a car dramatically causing over or understear .

[chenks]

i changed my tyres but put back on the same size (different make though), and i got the VSC and TRC OFF lights coming on.

i'm taking it into Toyota to get it looked at... as i already got the tracking rechecked and it's spot on.

[travman t sport]

so if i put the same size on 205/45/16 then there should not be any problems as said by mr.t as i cant see how a lowwer pro tyre would f*!"k the abs up and stop it from working.

[nrgizerbunny]

the profile you've got won't work.

you should have got 205/50/16 to keep the same profile as 195/55/16 which is what the car originally came with. The ABS compares different wheel speeds and if it senses that the rear wheels are spinning at a significantly lower rate than your fronts, it will error.

[shazzbaa]

so if i put the same size on 205/45/16 then there should not be any problems .......

I would agree with that .

Maybe the computer needs to be reset , not sure exactly how to do it but

try making sure the wheels are set straight ahead and then disconnect

the Battery for half an hour , then reconnect it .

I'm sure someone will post if it's any different .

[J26]

my cts has got 205/50r16 on front and 195/55r16 on rear and i hav no problems at all. as sed b4 i will ***** up all abs sensors if fron and rear rolling radius r different?try different tyre size and it might sort the problem???

[travman t sport]

so if i put the same size on 205/45/16 then there should not be any problems .......

I would agree with that .

Maybe the computer needs to be reset , not sure exactly how to do it but

try making sure the wheels are set straight ahead and then disconnect

the Battery for half an hour , then reconnect it .

I'm sure someone will post if it's any different .

iam going to have the same fitted agian and see what happens. its so odd tho when you first start the car up and drive it no lights on then about five miles down the road they all pop back on i think it must reset and then when you drive it thinks oh crap the wheels arnt going at the same speed.

[Corolla Chris]

Having different size tyres and indeed wheels will not screw the ABS operation up, the ABS sensor uses a hall type sensor in the hub that detects when the wheel is locking using the pick ups on the driveshaft!

[wilber]

think it messes up the vsc as it senses the wheel speed to determine if wheel loosing grip and adjusts accordingly, if doing it all time thinks it has fault and alarms up

[shazzbaa]

Having different size tyres and indeed wheels will not screw the ABS operation up, the ABS sensor uses a hall type sensor in the hub that detects when the wheel is locking using the pick ups on the driveshaft!

Huh?.....

If you have one size of tyre on the front and a different size tyre (ie. different circumference , pedant) on the back ,

this WILL confuse the ABS regardless of where the signal is picked up from . This is because the front and rear wheels (tyres , axels etc.)

have to rotate at different rates when the car is travelling at a certain speed (road speed)

If larger circumference tyres are fitted to the front axel , and in comparison smaller circumference

tyres fitted to the rear , the rear tyre will have to complete more rotations to travel the same distance

as the front tyres . The ABS will notice this difference in rotational speed and think the front tyres are skidding (fronts rotate more slowly than rear),

this is because under normal driving conditions both front and wheels (axles , tyres) should rotate at the same speed

in a straight line .

I suspect that the ABS is tolerent to very small speed difference between the front and rear , to compensate for things like

different tread depths and tyre pressures etc.

If you could fit 22inch wheels to the TSport , there shouldn't be a problem with ABS/Traction Control as long as you fit the same wheel/tyre combination to front & rear .

[T128]

215/35/18 no problem at all