Drawbacks to running a taller tire on rear of FWD car?

[Browning]

It only throws speedometer off in the taller than stock would be on the front, wrong or right? Reason I ask is I just found two under 300 mile tires for $30 and I will be needing tires before winter hits. Stock is 185/65/14 and the two I found are 190/70/14. My plan was to throw the bigger tires on the back and get two more later on if needed. The ones on the back now aren't too bad and should get me through winter.

 

What are the pros, if any,and the cons of running taller tires on the rear?

[greg1647545532]

What car? Does it have traction control?

[Browning]

98 neon.

[Green Bastard]

It doesn't seem like a big difference, I wouldn't think it would hurt anything (especially since they are not the drive tires).

[Cordell]

Well it depends on how much difference there is, but it'll screw with ABS and traction control if it has that, and will mess with the handling. Of course the closer the tires are, the less effect there will be.

[greg1647545532]

It won't affect abs because there's typically no wheel speed sensors on the rear. I don't think a 98 neon would have skid control; traction control will just be on the front if it exists. So I think you'll be fine.

[93 RX-7]

Uh...I'm pretty sure there needs to be a speed sensor on each wheel that has abs...

[Cordell]

It won't affect abs because there's typically no wheel speed sensors on the rear. I don't think a 98 neon would have skid control; traction control will just be on the front if it exists. So I think you'll be fine.

This is just outright incorrect information.

 

I don't know if the car has ABS or not. If it does you can not have different wheel speeds for it work properly. It was an option on a 98 Neon, and it would have 4 speed sensors if it does.

 

Uh...I'm pretty sure there needs to be a speed sensor on each wheel that has abs...

 

There weren't very many vehicles (usually trucks) that only had ABS on either the front or rear wheels, but there were a few when ABS first started becoming common in the early 90s.

[Furloaf]

Wouldn't taller tires in the back shift weight to the front? Logically then, you would want the shortest tires in the front and tallest in the back. Fucking genius right?

[93 RX-7]

Yeah, I was really trying not to call anyone a dumbass Scott. :-)

[Trouble Maker]

I don't know if the car has ABS or not. If it does you can not have different wheel speeds for it work properly.

 

This is just outright incorrect information.

 

Fixt.... Well I guess it depends on what you mean by 'properly', really the different tires might make a bigger difference than differently sized tires.

 

Will it fail or be unsafe? Very likely not.

Will it not perform at 100%? No, but this is ture for not only abs but the entire car as soon as you you put non stock tires on the car.

 

 

Protip. Just by sidewall difference those tires are closer in diameter than some stock tires at to the stock spare.

[Cordell]

Fixt.... Well I guess it depends on what you mean by 'properly', really the different tires might make a bigger difference than differently sized tires.

 

Will it fail or be unsafe? Very likely not.

Will it not perform at 100%? No, but this is ture for not only abs but the entire car as soon as you you put non stock tires on the car.

 

 

Protip. Just by sidewall difference those tires are closer in diameter than some stock tires at to the stock spare.

 

So it is going to work as designed with different sized tires? :dumb: This is how I took the question, and is how I answered it. I work on cars every day and telling someone simply "yeah you'll be fine go ahead" will get you into trouble. Will there be any ill effects? Maybe, maybe not, but when I bring up ABS as a possible issue, it's just that possible.

 

And space saver spares have been the cause of ABS issues as well, that is not good reasoning.

 

 

Now on a serious note, if it were me and it was $30 for some decent tires for my beater I would try it. Just know that the ABS could get much more sensitive, and with a weight shift in the car handling will be effected, how much you'll have to find out. Likely not a big deal at all even though people want to argue about what "could" happen.

[Trouble Maker]

Scott, I think we are agreeing here but just stating it differently.

 

Any system that fails with the stock sized tire and the stock space saver spare was a very, very poorly designed and tested system. I'm sure it's happened but that's just bad engineering.

[Cordell]

Scott, I think we are agreeing here but just stating it differently.

 

Any system that fails with the stock sized tire and the stock space saver spare was a very, very poorly designed and tested system. I'm sure it's happened but that's just bad engineering.

 

Ok.

 

If you consider how the ABS system works, it wouldn't be very useful if it would work with the space saver on it. Going from say a 27 inch tall tire on your average car to a 25 inch space saver you loose 6 inches or so of rollout on that wheel making it's speed off enough to make it think that it's slipping when it's not.

[93 RX-7]

Plus you are not supposed to drive fast or far on a space saver.

[Geeesammy]

We need a section for approved members to answer tech related questions.

 

It may or may not mess with the ABS but I'd rather play it safe if it was my money.

[Trouble Maker]

Going from say a 27 inch tall tire on your average car to a 25 inch space saver you loose 6 inches or so of rollout on that wheel making it's speed off enough to make it think that it's slipping when it's not.

 

There is tire diameter compensation logic that 'corrects' the speed of the slower/faster tire, so that while moving in a straight line at constant speed they all 'read' the same speed. This takes some time so before that happens the thresholds are higher to take into account a 'worst case' situation, usually something larger than the stock spare versus the stock regular tire. This is the typical base idea, but some makers have different concepts of how to handle this. But they will all have some idea of how to handle differently sized tires to avoid the false activation situation you are talking about.

 

But that's now, the systems in 1998 were (typically) much less sophisticated, well thought and thoroughly test as they are now.

[Browning]

Thanks every one. I am unsure about ABS on this car. I don't recall ever seeing a light on the dash for it but I would assume it's got it being a 98.

 

I decided to pass on the tires because of the possible braking issue. My 2 year old son rides in this car and I don't take chances when his safety is at play.

[93 RX-7]

Good choice.