Tyres

[Silver Surfer]

225/45/16 front

265/40/17 rear ( Can fit on Rim width 0f 9x17 to 10.5x17)

difference in diameter = 5.75%

Is this acceptable for the car's ABS/TCS ?
What's the standard Rim width on the 94+ rear alloys?


SS

[TheSebringOne]

SS, I think the tolerances are up to 5% and within this, it won't affect the TSC and maybe the ABS? Not sure exact size of oem rears 94+? its in the driver's manual, not at home now!

[Silver Surfer]

TSO,

I also thought it was a 5% tolerance but there many out there with 215/45/16 front and 255/40/17rear which measures out at 5.98% with no problem?!?

SS

[Kevin]

That's becuase it's not how the 5% rule works.

You take the ratio of the stock front tyres to stock rear tyres, ie the 'standard ratio'.

Then with whatever tyres you get, the ratio of the new tyres has to be within 5% of the ratio of the stock tyres, ie the 'new ratio' has to be within 5% of the 'standard ratio'.

[simonprelude]

Explained slightly better than me

That's becuase it's not how the 5% rule works.

You take the ratio of the stock front tyres to stock rear tyres, ie the 'standard ratio'.

Then with whatever tyres you get, the ratio of the new tyres has to be within 5% of the ratio of the stock tyres, ie the 'new ratio' has to be within 5% of the 'standard ratio'.

[Silver Surfer]

Good,

I'll get some wider 265 rear tyres then.

SS

[TheSebringOne]

Sorry Kevin, but without sounding a bit below the avearge IQ, then 215 45 16 (stock fronts) and 255 40 17 (upgraded rears) should be ok as SS stated? Thats on stock oems 94+ 16/17s combo.

[Silver Surfer]

That's becuase it's not how the 5% rule works.

You take the ratio of the stock front tyres to stock rear tyres, ie the 'standard ratio'.

Then with whatever tyres you get, the ratio of the new tyres has to be within 5% of the ratio of the stock tyres, ie the 'new ratio' has to be within 5% of the 'standard ratio'.

Just to be pedantic....do you mean 5% of the 5% (if the stock ratio is 5% for arguement sake)....ie +/-0.25% .

215/45/16 and 245/40/17 ratio is 4.67%
215/45/16 and 255/40/17 ratio is 6%
225/45/16 and 255/40/17 ratio is 4.43% (current)
225/45/16 and 265/40/17 ratio is 5.75% (?future)

As you can see, there is more than the 5% of the stock ratio (+/- 0.25%) change yet the cars are OK?!?

SS

[vic]

That's becuase it's not how the 5% rule works.

You take the ratio of the stock front tyres to stock rear tyres, ie the 'standard ratio'.

Then with whatever tyres you get, the ratio of the new tyres has to be within 5% of the ratio of the stock tyres, ie the 'new ratio' has to be within 5% of the 'standard ratio'.

hiya - wonder what is the significance of this 5% rule? How does it affect the abs/tcs and perhaps more importantly/interestingly why would it affect these systems if >5%?

cheers

v

[simonprelude]

If the ratio is greater than the 5% then this is outside of the allowed tolerance, ie the ECU will think that one set of wheels is spinning / skidding and cause the TCS to cut power.