Savino67

Hi, does anyone know how it works , do I have a sensor in the wheel or on the suspension . I just a tyre repaired and the chap stated that there wasn't one in there , strange ..

jvc300

The sensor is in the wheel. It's directly connected to the valve stem.

BudC

I thought it was part of the valve stem. BTW, do not use metal stem caps with the TPS system.

BenzV12

I do use this approved MB product :


and another item I have got



Good reminder on the metal caps, but my factory wheels came with the tiny metal caps though

jvc300

Sometimes, they are. I've seen the TPS monitor screw on, or mount to a valve. either way there should be a monitor connect to the stem on every wheel.

telemakhos

Some cars, at least mine, has a simplified TPMS. No additional hardware in the wheels. It just measures rotation speed at each end to determine if one tire is low or not. No direct measurement of pressure.

leapingpoint

that's what i have on mine too...................

threeMBs

There's obviously some confusion with TPMS here.

The OP is probably, based on words "tyre" and "estate", is not US based (GB maybe?).

All US W212 E-class are equipped with so called "Advanced" TPMS with sensor in each wheel with each wheels' pressure displayable on screen.

Non-US cars have TPMS as described by non-US based posters (based on E models specified, which we do not have in the US).

CEB

The US mandates a direct system which actively determines the tire pressure and alerts if the set pressure falls by 25%. Most sensors are about a half inch long and are attached to the valve stem and sit on the inside of the wheel.

Some other countries mandate or allow an indirect system which does not use additional sensors but uses existing sensors (abs etc) to determine the rolling diameter by comparing the rotational speed of the four wheels.

This indirect system is not as accurate and cannot account for temperature based or time based pressure loss. It also reacts much slower than the sensor based system.

TPMS has been mandated in the US since the 2007 model year by the TREAD act.
Since the sensors do not alert until you've lost a significant amount of air, you cannot rely on them to replace your monthly checks.AFAIK, the US is the only country that mandates the direct system and one of a very few that uses it.

hyperion667

sometimes I wish I didn't have those things......haha......always checking them!!!

the other week when I was at the tire shop some guy came in with metal caps on his stems that were fused together.....he wasn't happy when they told him whats happened and how they needed to break the seal and then sell him new kits for each wheel....