2010 PTT
Is it possible to put smaller tires on 19 inch rear?
285/40R19 are damn expensive. I don't need the performance.

255/45R19 are easier to find and cheaper.

 

Seems to be the same rolling diameter. I think it should be ok, but mehhhh on going narrow tires ...especially on a PTT. You could go with a lesser brand maybe.

 

I really like Hankook tires but the widest they have is 255. I switched to Hankook 10 years ago starting with the Boxster, and I have not feel the need to change to another brand. Hankook seems to give me the best bang for the buck. The price is very reasonable. The Pilots are great but it's just overkill for me.

 

Walmart has Delinte Desert Storm D8 285/40R19 103Y for $128.79 each. Those narrow tires might not stretch enough to fit the wider rear wheels...

Funny but I got a Lionheart 20" for less than $80 for the rear, size 295/35R20 last year. Maybe trade war consequence...

 

There is a wealth of tire information at www.tirerack.com. In particular, they offer rim width requirements for each tire size.

I have mounted "front tires" on wider rear rims on a Jaguar and Hyundai Equus with no issues over tens of thousands of miles.The limitation seems to be whether or not the tire can seat on the wider rim. Usually it can. But now you will find that your rim is the widest part of the wheel/rim assembly and thus more vulnerable to curb rash.

With my '14 Panamera S I wanted the narrower (lighter) front rims all around. Bought used oem rims on eBay for about $250 each.

 

My PTT comes with TPMS. When I take my car in to replace the tires, is there anything special that needs to be done? The tire shop should know what to do right?

 

They should know what to do. The competent ones that is...

 

The TPMS are clever little devices. They are essentially low power radio transmitters that use the valve stem as antenna. The power source is a battery embedded in a signal pod attached to the valve stem. When the car is at rest there is no signal sent to the car's ecu. Hence, you get a "no-signal indication" at rest. At about 15 mph and above the force of the rotating wheel activates the signal sender. What this means is that every time you put the car in motion the TPMS remeasures tire air pressure. So, when you mount new tires it continues to operate just the same as before without regard to whether the tires are old or new.

 

I assume the tire shop should re-use the valve stem? I thought they install new valve stems every time new tires are installed?

 

They are typically separate, unless the shop has those valves and TPMS factored into their mounting/balancing price.

As for the TPMS signal on some cars, they typically do a read out as I add air and not necessarily be in motion. Maybe Porsche has a funny way of when it decides to take a read of tire pressures but I think the TPMS I've installed on mine is not necessarily exclusive to Panameras.

 

Cars without TPMS often have rubber valve stems, which are sometimes replaced with new tires. Rubber valve stems are almost always "pressed" into the rim.

TPMS valve stems are part of the TPMS unit and are fastened with exterior threads, which in turn are sealed with rubber 0-ring gasket. TPMS units are almost always reused/reinstalled. Sometimes the rubber 0-ring does not seal. Often this is caused by loose threads on the valve stem. Sometimes the 0-ring is worn or age hardened. A light smear of silicon sealant on the 0-ring is good sealant insurance.

 

Sorry, you drive a PTT and say the tires are too expensive?

 

$129 for a tire that large is a great price, even though they went up from around $80. And the one that I got has M + S rating. (Wish my wife would be okay with changing all four). The original Michelins hate cold weather, even the milder ones we have here in Southern California. Feels like turning is going to rip the car apart when it's cold...

 

Yup. It's because I purchased it at almost 80% depreciation.