Another Same Tire Size Question

[cougarmandan]

I know its been asked before. I have searched and I can't find the answers I am looking for. I have an 03 300a, no traction control. The rear tires are shot. I took it in to the dealership to have its oil changed and an alignment set with the better specs I found on here. While I was there, I had them check the price on the rear tires and they tried to convince me to put on the same size as the fronts. I told them to hold off because I thought it messed up the abs. Is it just the traction control cars that have the problem? I had been thinking about it in the past but I had it in my mind that I needed to get a marquis abs module. My other questions is if the tires are switched on the rear and the abs issue is solved, how bad does this affect speedometer? And gas mileage? I have a used Diablosport tuner I haven't ever got out of the box from someone from the forum here (it was supposed to be set back to stock tune and reset so it can be used on another car). I think its supposed to be able to compensate for tire size. Anybody done this?

[Midnight]

backs, 245/55/18 BF goodrich

[fastblackmerc]

Tire size WILL NOT affect the ABS. It WILL affect the traction control, but since you don't have traction control you can use same size tires in the corners.

[fastblackmerc]

Depending on how much difference between the stock tire size and the new tire size will determine how much the speedo will be off. Tire size shouldn't have an effect on gas mileage.

[RoyLPita]

Let me know if you do change out your MM ABS module. I'll make you a deal for it.

BTW, the speedo on my MM is 2 MPH slower with stock size tires. with 235/50-18s, it will be 1 MPH fast. I may go that route next.

[LordVader]

The tires I have on for winter are 235/50 all the way around. It was just too hard to find matching treads on a decent all-season tire. I'll probably do a winter package this year, then I'll have three sets of tires around. I shouldn't run low on rubber for a while.

[cougarmandan]

That's good info guys. Tire Rack has the fronts (KDWS) on special for only 79 each right now. I ordered 2 with shipping and it was 180. That's just a little more than 1 correct sized rear. I wonder what kind of mileage these will give me. The car has 41k on it, I got it with 22k, but I don't know if they were ever changed.