Tire diameter messing up ABS?

[fireslave]

Just curious, has anyone ran the same tires on the front and back? the stock car has about a 2% larger overall diameter in the back, and I was wondering if the ABS system would have trouble if all the tires were identical...

[xjmxstac]

Do you mean tread width (e.g. 245mm, 265mm)? Rim diameter would be 17" or 18". I don't see how abs would react to a slight change in tire setup. If anything, VDC/TCS would be the first to be affected.
Modified by xjmxstac at 2:00 PM 6/3/2009

[fireslave]

im just saying that a 245/45/R18 isnt the same diameter as a 225/45R18, the 225 will be smaller because 45% of 225 is less than 45% of 245.

I know if the diameters are too far off of the stock numbers, ABS will be deavtivated because it is 'malfunctioning'

but i dont know how much of a difference it would take for this to happen. Do you guys think it would be a problem with the same size tires all around (the back is larger diameter on the stock car)

I would guess not, 2% isnt really that much... but I wanted to see if anyones done it.

[Tennz]

I run 245/45/18 on all corners with out a problem for the most part. If I know I'm going to drive like a mad man I turn off the TCS. It did stopped all the tire ware issues.


Modified by Tennz at 4:23 PM 6/4/2009

[xjmxstac]

im just saying that a 245/45/R18 isnt the same diameter as a 225/45R18, the 225 will be smaller because 45% of 225 is less than 45% of 245.

I know if the diameters are too far off of the stock numbers, ABS will be deavtivated because it is 'malfunctioning'

but i dont know how much of a difference it would take for this to happen. Do you guys think it would be a problem with the same size tires all around (the back is larger diameter on the stock car)

I would guess not, 2% isnt really that much... but I wanted to see if anyones done it.

Ahhh.... I see what you're saying. Now I wonder if you can reset the abs settings somehow. I know that the later 07-08 GT have a bigger difference in front/back wheel diameter. They have 18"x9" fr amd 19"x10" rr. Now if GT's have a different abs setting than a same year Base model, there has to be a way to reset it.

[mark456]

I've had my Redline for about 6 months now and have been reading these posts for a while and find them very informative. So I have just joined today to put forward my opinion on this.

I faced the same confusing dilema a few weeks back when I started looking for tires for my Vue Redline and after much research reading old threads and enquiries to various web sites, I went with 225/70-16 Blizzak DM-Z3. They are only 2.7% larger than the stock 245/50-18. My local dealer advised against this, said they were too tall and would cause problems and suggested using a 235/65-16 (Blizzak WS50 only one in this size and no stock) or 215/70-16 (more choices) but I didn't wan't to go that narrow. An other Saturn dealer in Toronto was offering 225/70-16 packages for Vue's so I figured it must be OK.mark456parking sensor

[fireslave]

I've had my Redline for about 6 months now and have been reading these posts for a while and find them very informative. So I have just joined today to put forward my opinion on this.

I faced the same confusing dilema a few weeks back when I started looking for tires for my Vue Redline and after much research reading old threads and enquiries to various web sites, I went with 225/70-16 Blizzak DM-Z3. They are only 2.7% larger than the stock 245/50-18. My local dealer advised against this, said they were too tall and would cause problems and suggested using a 235/65-16 (Blizzak WS50 only one in this size and no stock) or 215/70-16 (more choices) but I didn't wan't to go that narrow. An other Saturn dealer in Toronto was offering 225/70-16 packages for Vue's so I figured it must be OK.mark456parking sensor

If you change the size of all the tires on a car - say you got a 1 inch larger overall diameter on each corner of your saturn, this would not be a problem for the ABS, as the ABS is mostly concerned with wheel speed relative to the speed of the other wheels. There is generally a small portion of the algorithm that decides whether your rate of deceleration is reasonable (useful if all 4 tires lock at once, because there would be no speed difference) but nothing short of a monster truck tire is going to cause problems there. However, if you put big tires on the back of your saturn and not the front, the sensors would conclude the rear tires are going slower than the fronts, which is a problem for the ABS.

The only real problem with changing the overall diamater of all tires equally, assuming you dont get ones so tall that they rub, is that your speedometer reading will be off, in your case, you will actually be going 2.7% faster than your speedometer says you are going.

Its nice to hear that someones running the same size tires on all corners without problems though. My TCS is pretty much going to be permanently off anyways, so no big deal there.

[blastoff99]

I'm going to 245/45-18 when I get new tires, and have been assured that this will not cause any problems on my base model. However, I do not know for sure that everything would be ok on a car with VDC/TCS. These systems use wheel speed sensors, and they know what "normal" is. I wouldn't think this minor change would be enough to cause trouble, but you might want to check on "that other" Z forum.

One thing I think I DO know is that same size tires front and back will make your car more prone to oversteer. Since you have VDC/TCS, this may not matter to you.