BlueRidge

The recommended tire pressure for GLC 300 18 inch wheels is 32 psi all around, based on the info inside the flap over the gas cap. The suspension is tuned to the “run flats” that come with the car. If one switches to regular tires, instead of using the run flats, should you keep the tire pressure the same as that indicated on the flap over the gas cap (32 psi) or should it be a higher pressure because regular tires have a softer ride and the suspension is tuned to the run flats?

When I received my GLC 300 earlier this month, I had the dealer remove the run flats that came with the car and put on Michelin Premier LTX 235/60 R18 tires. I plan to put the run flats back on the car at the end of my 3 year, 30,000 mile lease.

Thanks for your assistance.

dieseldoc

Would run 32 all the around even without runflats

mikbar2

Ditto, 32 psi.

Ddmccormack

Am assuming you guys mean 32 all around cold, right? (so it gets up to 36 warm....?)

ajmtbm

How was the ride quality with the job right tires? Was it a noticeable difference?

I would love to go to standard tires just wish I had a solution for a spare

decorily

Why not go with the compressor and can of goo?

ajmtbm

Just worried I guess because it's different from the norm. . What if I get a puncture that the goo can't fix? Then I'm stuck on the middle of nowhere until someone shows up. Then again if I get a flat work the rft the same applies as I would wait for MB to come get me i g
How does the whole mess with rft work anyway? If 8am Sunday morning I get a flat in assuming they can give get me but they won't fix me until Monday? Or do they work 24x7? So if I'm more than 50 miles from home am i stuck?

dieseldoc

Runflats work well. Wife hit road debris today rear tire pressure dropped to 6. Car was able to be driven to dealer 10 miles away.

BlueRidge

Thanks to all for the suggestions on proper air pressure.

ajmtbm: I never rode on the run flats because I had the Mercedes dealer put on the Michelins before I picked up the car.

I bought an air compressor that attaches to the car battery (Viair 88) and a Slime tire plug kit to deal with most small punctures. I also bought a can of Slime 60190 Quick Spair Tire Inflator (20 oz.) as a back-up in case I could not find the leak. But none of these are as good as having an actual spare in case of larger punctures or sidewall problems.

mikbar2

The wife had a flat, cut on one tire, on her rft's last week. All the goo in the world would have left her stranded. The rft's got her home. I've never been a fan of rft's but now I am. See my thread "Crappy MOE's"

dieseldoc

Agree. RFTs saved my wife today. Have no plans on switching to non runflats

Sigp232

which run flats do you have?

dieseldoc

19 inch wheels with Pirelli Scorpion Verde. Very pleased and I am normally a Michelin tire person.

ajmtbm

were they able to repair the tire or did you have to get a new one?
i could definitely see the advantage of run-flats for getting where you need to be in case of emergency - makes a whole lot of sense from that aspect.

I guess the only thing that scares me is the dealer left me under the impression you get a hole you cant repair the tire. and of course being AWD you would have to replace a pair.

i have the 18" and right now there seem to be 2 brands that offer replacement, not a big fan of having limited choices either.

dieseldoc

Replacing the tire. Tire was not repairable. I do not have a problem with it. I have wheel and tire plan.

mikbar2

According to Americas tire a puncture can be repaired if not with in 1 1/4 inch of the side wall edge. I am running Bridgestone Drive Guards with a 60,000 mile tread warranty. IMHO they drive better than the MOE's. $240 out the door everything included such as road hazard warranty and lifetime alignment and tire replacement.

ajmtbm

wow - mileage and road hazard warranty - that's awesome - of course they dont make them for the 18" wheel...

mikbar2

Americas Tire is owned by Discount Tire. Have you checked with them?

chillysyrup

Tire pressures are always quoted cold.

ajmtbm

went to the manufacturer's website and they dont list drive guard as available in that size.

Ddmccormack

Right, by manufacturers. My question was to the post originators...

larrypmyers

Basic rule...tire pressure always checked cold. Optimally first thing in the morning, prior to the vehicle being driven.

Yes, pressure will increase when the vehicle is driven. How much depends on outside air temperature, how fast the vehicle is driven and how heavy the vehicle is laden.

bips

My post is limited to the OP's tyre pressure question, rather than having another of our debates for and against RFT.

My understanding of the conventional wisdom for regular tyres was that one should slightly over-inflate compared to manufacturer's specifications, because they were aimed more at comfort, and 34psi say, rather then 32, would mean less sidewall flex and thus less heat build-up and lower tyre wear. Perhaps also slightly better handling, at the cost of a slightly firmer ride. This seems to be the view of most car-savvy people that I know.

I quickly discovered that this generic advice wasn't a great idea with RFT. The ride was too harsh. Clearly there's less wiggle room with RFT.

But I've recently switched to non-RFT, and am wondering whether or not the generic conventional wisdom now applies to my GLC. A couple of posts here suggest no. Are these views based on experience, or a different understanding of tyre and suspension theory?

ajmtbm

so based on the vehicle pressure gauge looks like i have higher pressure in the rear (42?) and maybe 34 or 36 in the front (I keep forgetting to check ice cole 1st thing in the am i will tomorrow). im assuming the rears are too high. is there any downside to riding like this?

if its a problem can i just let some pressure out or will the tpms then think i have low tire pressure?

dieseldoc

What size wheels do you have and what size tires?