Front vs rear tire size

[MercThunder]

Hi guys,

Is there any reason why not, or has anyone tried, having the front tires the same size as the rear (in any configuration)? I've never been able to figure out Ford's reasoning for the differing size front to rear (although there's lots of times when Ford's reasoning is confounding).

[fastblackmerc]

Hi guys,

Is there any reason why not, or has anyone tried, having the front tires the same size as the rear (in any configuration)? I've never been able to figure out Ford's reasoning for the differing size front to rear (although there's lots of times when Ford's reasoning is confounding).

New here huh???

The '03 Marauders can use any size front or rear tires that will fit. You can also use the same size front and rear.

The '04 Marauders, or any Marauder with traction control, need a 3 - 5% difference in tires size (larger on the rear) so the traction control does go nuts. If you decide to use the same size front & rear on an '04 you will need to do one of 3 things:


Manually turn off traction control everytime you start the car
Get traction control turned off in the tune (don't actually know if this is
possible)
Someone made a circuit board to insert in the circuit that turns off the traction control automagically.


Since your signature doesn't say which year MM you have to pick which scenario fits.........

[RubberCtyRauder]

They did it for looks..the stance slightly raked..lower in front than rear. Same size tire in rear on these cars looks off to me, too much wheel well gap unless you lower the rear height sensor to adjust air springs so less gap shows. Above info from fastblackmerc is how to work with it.

[Bluerauder]

Not just the '04 Marauders need the different sizes. The '03 300B's also have Traction Control and need the 3-6 % difference in tire size to keep the TC from going wacky.

[MercThunder]

They did it for looks..the stance slightly raked..lower in front than rear. Same size tire in rear on these cars looks off to me, too much wheel well gap unless you lower the rear height sensor to adjust air springs so less gap shows. Above info from fastblackmerc is how to work with it.


Thanks for that....I was pretty sure that was the correct answer (in spite of being new here....), but thought I'd solicit some experienced answers. For some reason, mine seems to look high in the front, although I've gone with the factory tire sizes. Haven't done anything with the suspension yet, although I do have all the parts and pieces.

[MercThunder]

Not just the '04 Marauders need the different sizes. The '03 300B's also have Traction Control and need the 3-6 % difference in tire size to keep the TC from going wacky.

I should be good then, since mine is an 03 300A

[ctrlraven]

Also with running the same size as the front in the rear, your speedometer will be off slightly. The computer is looking for X amount of revs per mile from the 245/55-18, the 235/50 has a smaller diameter and will rotate faster so your speedometer will be reading slightly faster than you are actually going. Some may say that's okay but over time it can add extra miles/km.

Getting a tune for the car will allow you to make the adjustment for different tire sizes very easy via electronically.

Most who run the same size tire around do it for the main purpose of extending the life of the tires by being able to rotate them and replacement.

I've ran 235/50 in the rear for a few months after the factory rear tire went on backorder for the longest time. I've had these tire size combos as well
F235/50 ~ R255/55 (rode smooth)
F255/45 ~ R265/50 (rode rough but handled great)
F255/45 ~ R255/55 (half & half, tight/hard in the front, loose/smooth in the rear)

[fastblackmerc]

Not just the '04 Marauders need the different sizes. The '03 300B's also have Traction Control and need the 3-6 % difference in tire size to keep the TC from going wacky.

Any MM with traction control.........

[345HP87SSAC]

Mine is an 03 but I run 255 all four corners, cause I am old school and I like a little sidewall.

[ctrlraven]

Mine is an 03 but I run 255 all four corners, cause I am old school and I like a little sidewall.
255/45 or 255/55?

[EMAS]

New here huh???

The '03 Marauders can use any size front or rear tires that will fit. You can also use the same size front and rear.

The '04 Marauders, or any Marauder with traction control, need a 3 - 5% difference in tires size (larger on the rear) so the traction control does go nuts. If you decide to use the same size front & rear on an '04 you will need to do one of 3 things:


Manually turn off traction control everytime you start the car
Get traction control turned off in the tune (don't actually know if this is
possible)
Someone made a circuit board to insert in the circuit that turns off the traction control automagically.


Since your signature doesn't say which year MM you have to pick which scenario fits.........

#4. Get the ABS/Traction control module from the corresponding year GM or CV run the same size tires front and rear and have active traction control.

[lifespeed]

#4. Get the ABS/Traction control module from the corresponding year GM or CV run the same size tires front and rear and have active traction control.

I asked about this and nobody seemed to know, or thought it wouldn't work. Are both systems controlled by the same electronic module? Who has actually done this?

[EMAS]

I asked about this and nobody seemed to know, or thought it wouldn't work. Are both systems controlled by the same electronic module? Who has actually done this?


The ABS module is what controls the traction control. The wiring diagram for the 04 GM/CV is the same as it is for the 04 MM.

So it will plug right in and its programming is for matching tires sizes front and rear so it should work just fine.

They are cheap on Ebay, so if I had a MM with traction control I'd probably give it a try.


http://www.ebay.com/itm/03-04-GRAND-MARQUIS-ANTI-LOCK-BRAKE-PART-ASSEMBLY-ABS-W-TRACTION-CONTROL-110849-/281760247621?hash=item419a382f 45&vxp=mtr is the first one I came across with traction control.

[fastblackmerc]

The ABS module is what controls the traction control. The wiring diagram for the 04 GM/CV is the same as it is for the 04 MM.

So it will plug right in and its programming is for matching tires sizes front and rear so it should work just fine.

They are cheap on Ebay, so if I had a MM with traction control I'd probably give it a try.


http://www.ebay.com/itm/03-04-GRAND-MARQUIS-ANTI-LOCK-BRAKE-PART-ASSEMBLY-ABS-W-TRACTION-CONTROL-110849-/281760247621?hash=item419a382f 45&vxp=mtr is the first one I came across with traction control.

So you really don't "know" if it will work?

[EMAS]

So you really don't "know" if it will work?

No I don't "know" if it will work from trying it but based on my knowledge of how the Ford ABS/Traction control works and the fact that the wiring/connectors are the same I'm 99% certain that it will work.

The only difference that there could be is in the programming. The wheel speed sensors/tone rings are the same for the CV/GM and the MM.

[lifespeed]

No I don't "know" if it will work from trying it but based on my knowledge of how the Ford ABS/Traction control works and the fact that the wiring/connectors are the same I'm 99% certain that it will work.

The only difference that there could be is in the programming. The wheel speed sensors/tone rings are the same for the CV/GM and the MM.

By any chance do you know what alloy the tone rings are made of? I will be fabricating a pair of ABS tone rings to go on my Ford 9" floating hubs.

[daddyusmaximus]

Mine is an 03 but I run 255 all four corners, cause I am old school and I like a little sidewall.

255/45 or 255/55? Photo please.