traction control ques, 2 diff size wheels??

[stevie.w]

right i got a flat the other day so ive put on the spare, but its a 16" and the rest are 18s although with the low profile tyres the difference isnt that great, but ive noticed now that when i start to drive my car for about the first 30secs the wee traction control orange triangle flashes and the car holds back, but then it passes and drives normally until next time i go to take it out for a drive, so is the 2 different wheel sizes giving my ecu wonkey readings at start up or whats going on

 

[gazjones]

think the ecu will be thinking the spare tyre is spinning as its rotating slightly more but then prob figures out the cars now loosing traction best bet just turn it off till you get wheel replaced!

 

[stevie.w]

cheers for quick reply gaz, yeah thats what i was thinkin, but would it only do this when i start driving, why doesnt it do it all the time or does the ecu figure out theres a difference and stop bringing up the alarm, it only does it for about the first 30 secs of each journey then goes away

 

[gazjones]

probably ecu working out its not spinning after 30 seconds of driving

 

[stevie.w]

right o, cheers foe help, ill hopefully have the 18s back on it again tomorrow until then ill keep the tcs switched off.

 

[gazjones]

keep it off all the time lol not wet enough for it to be on yet lol

 

[Leigh15]

Just hope your ABS doesn't get confused! It's a dealer reset if it does

 

[m0rk]

ABS will be confused.... really bad idea....

 

[lukey]

you should always put a spare on a back wheel on a front drive car, is it back or front

 

[si-mate]

Isn't it illegal to have different sized wheels across the same axle?

Don't know how space savers get away with it though

 

[TheOtherSimon]

Before you drive the car again, put the spare wheel on the back, otherwise you are going to kill yourself.

The tyre on the spare wheel has a totally different grip to the normal wheel, and the TCS system is complaining that it is seeing one of the wheels slip. What it is warning you of is that you are going to get completely different braking efficiency on the two sides, and you will lose control.

It is not safe to drive it as it is.

The diameter of the rims has nothing to do with it, it's the circumference of the tyre that is important.

Simon.

 

[kempos]

fair point his wheels are 18s so a 16 spare will have a slight difference in grip but stevie said it was only for first 30 secs so no grip issues unless he starts up and nails it v bad for engine anyway then.

 

[Sisson]

The tyre on the spare wheel has a totally different grip to the normal wheel,
Simon.

Luckily my spare wheel is a full size 16" rim with the same size tyre on...