[quote]ORIGINAL: sikpuppy

according to the dealership, also recalibrates everything else, including the ABS, traction control, and electronic stability program.

Been thru this with Mercedes - ABS doesn't care what size tires you use just as long as you use ALL the same size on the SAME car. ABS isn't god - it can't tell how fast you are going only how many impulses it gets from the hall sensor. Taller tires mean SAME number of impulses but you actually travel further. Traction control runs off the ABS sensors and ESP if the wheels are all the same weight and tires the same tread design on all 4 wheels it would have nothing to complain about either. What you are doing is fixing the speedo readout and possibly a trans shift point We had a Volvo that went into overdrive at 57 MPH to be sure anybody(?) driving that slow did get overdrive. Obviously if you used tires that threw that off you may not get overdrive within the legal limit - well it's a big deal for manufacturers at least.

As for the software any chip that takes a program can be reprogrammed - Besides DCX HAD to set the parameters in the first place - they DO NOT MAKE THE TIRES.

Keep bugging dealer(s) till you get what you want. It's in their best interest too - there is a thing called competition and dumb dealers are a liability. Remember they used to sell K cars.

 

Yep and FORD sold the pinto, GM sold the corvair. hummm list could go on and on. Will see what happens car is at dealer for 3500 mile service and this service tech said can be reprogrammed. In fact he said if we put on the wheels tires would have already be reprogrammed. Guess these guys don't talk over coffee.

mike

 

OK, sorry it took so long to get back on this. As everyone here knows by now, I’m not here to make friends, I don’t work on anybody in here’s car so that is not an issue and I don’t care if you believe anything I say. So, with no reason to BS anyone here is the real deal, you CAN change tire size, BUT, only to a size that was available on a LX model. If you bought the low line and installed some 20’s from a R/T then that would work. If you spend for some 22’s or 24’s then you are out of luck. The LX line does not have the option of simply putting revs per mile like most of the other controllers out there. In case anybody’s dealer is having trouble the STARscan needs to be up to date and the change info is located in the FCM/Central Gateway (last place you would look).

Now, to via500, the ABS on this car IS God. It controls everything and it DOES know exactly how fast you going and it is important to be accurate for things like the stability program to work properly. Some functions of stability are not available at some speeds, so knowing exactly how fast is an issue.

Yes, DCX does provide some ability to change however they only are required to allow change to OE sizes. Also not ANY chip can be reprogrammed, the end user would have to know the exact protocol used to burn the chip initially and know what he/she were doing once in there. DCX is one of the few who highly guard this info as you don’t see anybody out there who can reprogram chips for Chrysler’s (although I am always looking for somebody if he/she ever do figure it out).

PS, anybody looking to do real tall 22’s or 24’s, trimming that upper BJ stud isn’t a big deal, just leave a few threads below the nut and try to keep the threads clean so I can still get the nut on/off if needed. Thanks all.

 

Some poeple just don't read, no ABS is NOT god on ANY car. No system out there yet actually "READS" the pavement going by, all they do is count impulses of the HALL EFFECT SENSOR triggered by the rotor/hub assembly. therefore it can only report what you tell it to report. In other words you TELL it "X" numer of impulses equals "X" MPH and that's what it reports. It can do nothing more. There is no way for it to determine actual MPH. Get it wrong and it won't care because it doesn't know it's off, it will simply execute it's program. And as I said in the Volvo example, it's in your best interest to CORRECT the speed readout to equal the actual pavement speed since some things such as shift points ARE determined on the INDICATED mph readout but you want them to occur based on actual speed.

 

No I read correctly. In your opinion dealing with what you know, ABS works one way. I happen to know Chryslers ABS system fairly intimately, that is my specialty. The ABS system does not measure road speed but unlike most systems that just transmit tone wheel square wave to another module for translation, this module actually does it's translation and the actual MPH needs to be fairly accurate for the stability program to function properly. You may know Volvo's system fairly well, but you don't know Chryslers----quit instructing on subjects you have not been taught yet.

Yes, I have worked for other manufactures’, they are NOT all the same. In fact, many are very different. BTW, it’s not “better� if the trans know actual road speed, it’s pretty damn important. [8D]

 

Dodgemech,


Any update on reprograming RT computer for oversize wheels/tires??

My 265/35WR22 tires only rotate 708 Revs Per Mile rather than the OEM 734. So my RT is going 3.7% faster than indicated (36.3 at 35; 57 at 55; & 67.4 at 65 mph). With that stupid 160 mph speedo, I can barely tell if its on 55 or 57!

Everything else seems to work just fine! If I jam on the brakes, does the Magnum ABS, for example, care that I am really going 57 when it thinks that I am only going 55, and that my tires have better traction!!??!!

In the past I liked to cruise I-40 at 72. Now I park the needle on 70 and automatically get 72.6! How handy is that!!??!!



Thanks for your patience, and sharing your knowledge with us!

 

Aside from the obvious inncorrect speed with the larger tires, one good point is you are racking up less mielage on the odometer. Of course your projected gas mileage will look like it is suffering, but you know the reality!

 

I'm just glad that the first owner had the guts, money, and knowledge to go for such a radical wheel/tire!!

Until now I thought that 45s and 17s were the limit to which any sane person would want to go!! So call me "Crazy!!"!! Whatever, I sure am a happy retiree!!

What I don't understand is why Dodge went with such a tall wheel combined with a narrow (225), tall (60) tire!!??!! Maybe they thought that the Magnum was a Mini-Van replacement!!

Hope that you are right about the gas! It certainly rolls along effortlessly!!

I'm using 33psi, even though they are 102W, to avoid pothole bruises. The footprint looks good at 9" wide and 5" long.

 

Reprogramming tire is NO PROBLEM. The Starscan has been updated for a while now and it is very easy to do.

 

Isn't there just a set of pre-programmed tire sizes to choose from, on stock size wheels, or can any wheel & tire combo be selected?