Gotta love electronics; Tires Size Rant!

When the wife unit bought her new Nissan Versa, I was all happy cause I have a fresh set of 15" Blizzacks that were used on here 202 Protege to toss on the Nissan since the rims are 15 inch. How could this not work?

Turns out that by dint of tire pressure sensors, tire diameter and traction stability, the Blizzacks I have will not work. Diameter is different than stock. The computer is going to decide that the wheel speed, speedometer and rpm do not all harmonize, and limit the vehicle to a limp home mode.

I have not looked yet, but I have the feeling that this is also going to limit me to some weird and expensive rim options when it comes time to buy.

I love progress.

This is partially what motivated me to buy my Honda Fit in new 2007, no TPMS. 2008 and up models are required to have it and I just didn't want to deal with it. I can run whatever I want for rim and tire size (not to mention pressure) and have no trouble with the car.

Yes, progress does suck.

Strange, they should be able to reprogram the ECU to handle the tire change.

Usually as long as all 4 tires are the same diameter, a simple reset of the TP monitors will compensate for the differences and calibrate accordingly.

Since not every tire in a particular size is going to be EXACTLY the same, I would think that as turboswede says...the ecu or whatever should be re-programmable. I can't imagine, under under government coersion(sp?) that car makers would use a system that doesn't ever alllow for a snow tire or a tire that MIGHT be slightly bigger or smaller than what came on the car.

But, yeah, near useless electronic "nanny" devices are some of the reasons behind my considering used over new...a tiny budget is the other reason.

If you change all four tires at the same time, the car won't be able to tell the diameter has changed unless it's using GPS for a speedo.

My son has a Kia with TPMS and he just swaps to whatever wheel and tire comb he wants (all 4 the same) and drives it .The TPMS light is on constantly, but everything else behaves normally.

TPMS- tire pressure monitoring system. Nothing to do with tire size.

iceracer wrote: TPMS- tire pressure monitoring system. Nothing to do with tire size.

According to Nissan, it is both the tire pressure monitor AND the stability control that is going to mess with my plan.

The story from NISSAN:

As part of the safety enhancing stability control the wheel is being monitored for revolutions, This is compared to the speedometer and engine rpms. If the numbers do not add up to the same as what came from the factory with the factory diameter tires, then "Something" is wrong and the computer puts you in limp home mode. In other words, if the car is going faster or slower for a given rpm ( as would happen if the tires were taller or shorter than the factory rubber)

I know the answer is to just go buy a new set of tires, but damn, this is annoying and I bet it get worse with age.

Sounds like a good reason to trade it in on something less nanny state-ish. Well, at least to me.

Sounds like my wife won't be buy a Nissan when she gets a new car in February.

I changed the wheels and tires on my 2010 Ford Transit Connect from 15" to 17" a couple months ago and didn't even put the TPMS sensors in the new tires. I haven't had problems other than the idiot light coming on. Funny part of that is that if I put the TC in the garage where the old wheels and tires are stored the TPMS will reset. It takes about 50 miles for it to come back on.

NOHOME wrote:

iceracer wrote: TPMS- tire pressure monitoring system. Nothing to do with tire size.

According to Nissan, it is both the tire pressure monitor AND the stability control that is going to mess with my plan. The story from NISSAN: As part of the safety enhancing stability control the wheel is being monitored for revolutions, This is compared to the speedometer and engine rpms. If the numbers do not add up to the same as what came from the factory with the factory diameter tires, then "Something" is wrong and the computer puts you in limp home mode. In other words, if the car is going faster or slower for a given rpm ( as would happen if the tires were taller or shorter than the factory rubber) I know the answer is to just go buy a new set of tires, but damn, this is annoying and I bet it get worse with age.

The engine speed-speedometer speed relationship should stay the same, you shouldn't have a problem.

Changing tires doesn't have any effect on the gear ratio between the engine and the speedometer cable coming from the transmission.

It's true that your actual speed for a given engine speed will change, but your indicated speed should stay the same. For example, if your tach says 5,000 rpm and you're speedometer says 80 mph, then putting bigger tires on the car would make the cars actual speed increase at 5,000 rpm. However, the indicated speed would still be 80mph.

I don't see how the car would know anything had changed...

Exactly. There's no feedback on the actual ground speed of the vehicle. As long as all of the tires are the same diameter as each other, the car has no way of knowing anything's changed. It simply knows that all the wheels are turning within the correct speed range of each other. Unless, like I said earlier, the car's double-checking the road speed with GPS. I find that unlikely - although it's plausible.

I think TPMS sensors have to be mated to the vehicle, otherwise you'd be reading everyone else's pressures too So it makes sense that simply bolting on another set of wheels and tires might throw a TPMS error. But it's not due to a diameter change.

Honestly, I like the TPMS on my truck. It's great to be able to monitor the state of the tires on a long trip. We even tried running a setup on the trailer.

Though I'd chime in and say go for it. I've been a Nissan tech for the last 3 years.

If all four wheels are the same size the car will not know the difference. Running without TPMS sensors will only give you a light on the dash, thousands of Canadians do the same every year. You might have to re-registered the TPMS sensor ID's when it comes time to put the summer tires back on, maybe not. Your speedometer will read off, that's about it.

The ABS/VDC/TCS gets it's speed signal from the wheel speed sensors at each wheel. I don't have the manual in front of me, but IIRC the VSS sensor on the transmission sends it's signal directly to the "Integrated Meter" (instrument cluster) then to the TCM and ECM via CAN lines.

DeadSkunk wrote: My son has a Kia with TPMS and he just swaps to whatever wheel and tire comb he wants (all 4 the same) and drives it .The TPMS light is on constantly, but everything else behaves normally.

Same on the Hyundai that I have. My winter tire OD is about .5" taller than the summer tires...no sensors. I have a light and no other issues.

Take the TPMS sensors out and have all 4 installed on the spare.

^ I like this.

We had our TPMS sensor CAUSE a failure. The collar that spins down over the threads to lock the sensor to the rim suffered from corrosion, split, and allowed the tire to deflate. At least the TPMS was able to tell this was happening in real time! Took em out, put in regular valve stems. Covered light with black vinyl! Wouldn't have had a tire failure had I NOT had the things on the car. I check my pressures regularly anyway.

vwcorvette wrote: We had our TPMS sensor CAUSE a failure. The collar that spins down over the threads to lock the sensor to the rim suffered from corrosion, split, and allowed the tire to deflate. At least the TPMS was able to tell this was happening in real time! Took em out, put in regular valve stems. Covered light with black vinyl! Wouldn't have had a tire failure had I NOT had the things on the car. I check my pressures regularly anyway.

This is a recall on Rogues and Muranos. Also, if you live in a "salt state" and the sensors have been on for more than 3 years or so, good luck getting them off without destroying them. You mostly have to take them off in the first place because they've started leaking.

I was able to have the TPMS system eliminated on my Cayman, but you have to get into the main computer to do it.

Post #7: http://forums.rennlist.com/rennforums/porsche-cayman-s/394014-can-you-run-winter-tires-w-o-tpm-system.html

I couldn't see spending an extra $400 for TPMS sensors for snow tires and then again for track tires. And the warning light would have driven me nuts. Now it's as if the system never existed and I monitor my pressures the way God and Ferdinand intended: With a tire gauge.

I'm sure that a friendly tech at Nissan could do it (unofficially) with the dealership's computer, but you probably need to find the sequence online yourself. I doubt that there are lot of Versa guys doing this, so it's going to take some searching.

I turned off the TPMS on my Corvette with my friend's Tech II. I couldnt be happier.

The Fiesta has a seperate fuse for the TPMS. Hmmm.

Good golly. All this to change the tire size?

Sounds like a good application for the .45 acp.

You don't have to do anything to change the tire size. Sheesh. Just change them. The car won't care, although your speedo will change in accuracy. Just like speedos have done for decades when you change the tire size.

Now, if you want the TPMS system to work, you need to set it up. That's the case whether you're changing the tire size or not.

I may have missed it, but is a "set" two or four tires? Four is easy. Two requires rolling diameter to be the same, or similar.