Just installed 19" Hankook V12's and was wondering what proper tire pressure should be. My 17's were 30F / 35R.

 

It should say on the sidewall of the tire typically, but i tend to run about 35 psi in all corners regardless

 

34 psi front & 39 psi rear...well thats my set up

 

44/41 if they are 50 psi max, i prefer a stiffer tire

 

I'm trying to figure out the same. I hate that there are 50 different pressures run by 50 different people but no straight recommendations like with the factory 17 inch wheels.

 

the hankook's have REALLY soft sidewalls. that being said, i run 30 in the front, 31.5 in the rear, ice cold. when warm, the pressure reads about 32/33.5.

when running more than 34/36 cold with these tires the contact patch is reduced considerably.

 

First only the max pressue and max load are found on the tire markings, but Crazy has the right idea about even tire pressure.

The tire info on the door jamb is almost always based on a Federal Statute, that describes how to determine correct pressure based exact tire selected by mfg, and max front and rear axle weights. For the C300, max rear is always greater than max front load, thus the higher rear pressure. But for driver only, front axle load is greater than rear axle load, and for that type of driving, you can actually front bias the tire pressure.

If Norm01 and/or Joejitsu (ever heard of Royce Gracie?) provide the following tire info (from the tire markings), front and rear, I'll determine what the door jam placard pressures would be for those 19" tires, and what you should run:

size [ (P)255/30/19 ] note if there is a 'P' in front of the basic width.
load rating [88, 91, 95 etc]
tire type [SL or XL]

.

 

I recently got a pm request from someone with 19" tires, looking for suggested tire pressures. He impied his car came with 18" AMG's. He also said he drove solo most of the time.

Understand that at the car's MAX load condition, stated in the B-pillar placard, has the typical 2 occupants up front, but adds 3 people (150 lbs ea) directly above the rear axle, and full rated cargo load rearward of the rear axle. Based on simple leverage, this cargo weight will put about 115% of value at the rear axle, and will provide about 15% of value as an uplifting force at the front axle, as calculated by MB for the Federal standard for car tires. The result is very high rear tire loads and pressures required.


----- First, determine actual 18" tire load rating at MB specified pressures ----


1.0 ---- 18" (AMG) OEM Tires

Spec: F = 225-40-18 92Y-XL R = 255-35-18 94Y-XL

1.1 ---- MB Suggested Pressure, for MAX CAR LOADING

F = 36 psi
R = 41 psi

1.2 ---- Allowed tire Load, per table: Mega-Tire/Presssure Table

F = 36 psi, 1190 lb ( 1389 max @ 42 psi ) 92-XL
R = 41 psi, 1433 lb ( 1477 max @ 42 psi ) 94-XL

1.3 ---- MB-psi based on Gas Cap Info, for (2-3) 150 lb riders and ~1/3 rate luggage in trunk:

F = 33 psi
R = 38 psi

1.4 ---- Allowed tire Load, NORMAL CAR LOADING, per Mega-Table:

F = 33psi, 1157 lb ( 1389 max @ 42 psi) 92-XL
R = 38psi, 1356 lb ( 1477 max @ 42 psi) 94-XL


---- Now use 18" tire loads and table to back calc 19" psi values ----


2.0 ---- 19" Hankook Tires (not OEM)

Spec: F = 235-35-19 91Y-XL R = 265-30-19 93Y-XL

2.1 ---- Psi for Max Car Loading (see 1.2 )

F @ 36 psi, 1201 lb vs 1190 req'd, ( 1356 max @ 42 psi) 91-XL
R @ 42 psi, 1433 lb vs 1433 req'd, ( 1433 max @ 42 psi) 93-XL Note tire is at load limit

2.2 ---- Psi for Normal Car Loading ( see 1.4 )

F = 35 psi, 1168 lb vs 1157 req'd, ( 1356 max @ 42 psi) 91-XL
R = 39 psi 1356 lb vs 1356 req'd, ( 1433 max @ 42 psi) 93-XL



---- now my interpretation of proper pressures for the listed 19" size ---



3.0 ---- KK2 suggested 19" pressures, for listed tire specs, solo driving

For solo driving, it is obvious based on visual static tire bulge, that the front tire sees more load than the rear. So I say go with the "normal" front tire load of 1168 lbs, and use it F and R. This provides a 4672 lbs total tire load capacity.

3.1 ---- KK2 tire pressures for 1168 lb load, 19" tires listed, F & R :

F = 35 psi (see 2.2)

R = 35 psi (33 psi per chart for 93-XL, but use 35psi for rim protection)

This is a starting point, and presssures should be adjusted up if edge wear occurs. Also, go for minimum specified neg camber, based on very low aspect ratios. Finally, do not load this car to MAX condition with 19" tire spec listed, for consistent operation, due to rear tire at max load capacity.

.

 

Front Tire Size 245/40 R18 Michelin All Season
Rear Tire Size 265/35/ R18 Michelin All Season

Solo Driver
Front Tire Pressure 33 PSI
Rear Tire Pressure 39 PSI

The dealer's service department after C Service said front tires were feathering. The note on the Service Order said front tires wearing on outside.

I had a four wheel alignment. The alignment shop said have the tire shop reverse the tires on each wheel. Take the left front tire off the rim and reverse the tire. Than have the right tire taken on the rim and reverse it.
The tires have less than 5,000 miles on the front.

The tire dealer said there was wear on both sides of the front tires. The tire dealer recommended that I add 4 pounds to the front and the rear to even the wear out on the front tires. The tire shop suggested that I recheck the tires is 5,000 miles.

The front tires are now at 37 PSI and the rear tires ar 43 PSI. The maximum tire pressure for the tires are 50 PSI.

Is this the best way to correct the wear or was the alignment shop correct? I can't tell if there was even wear on both sides of the tires.

 

Sound like you are in the wrong forum, but it's a common problem across classes.

Feathering is a distinct wear pattern:

> mostly on outer edge, but also on inner.
> mostly front tire, less on rears
> due to tire rotating contact, increases with miles w/o cross rotation
> usually on wide, low aspect ratio tires
> wear pattern only fixable by reversing tire's direction of rotation
> can be felt on outer edge of top of tire, using light finger pressure:
>>> rought on back stroke, smother on front stroke.


Confusing, but if he swapped front tires without changing direction of rotation, he did very little to cure problem and feathering will continue to increase. I the tires are directional, then that's all he could do.


I can see increasing the front tire pressure, but watch & feel to see if it makes it worse. No reason to increase rear, unless wear pattern was bad, and/or feathering was there.



If you have directional tires, the only thing you can do up front is reduce negative camber($$kit req'd) and minimize toe-in. Next time be careful about directional tires, only buy them if they have very obvious tractor like V grooves in the tread.

.

 

The tires are Michelin Sport All Season Plus.
The Alignment Shop said to change the direction of each of the front tires. Reverse the direction of each tire on the same wheel. The left tire will stay on the left side only the direction will change. The same for the right tire.
The tires were under extended warranty and recently purchased. The alignment shop suggested that I return to the tire shop to have the front tires direction change.

I told the tire shop what the dealer and the alignment shop said. The tire shop said just adding additional 4 pounds of air will even the tires out.
The Manufacturer recommends about a six pounds higher pressure in the rear tires over the front tires.
I am not sure if the tire dealer gave me the right instruction to correct the wear by adding air rather than changing the direction of the tires.

 

I changed the the tire pressure to:
Front Tire Pressure 37 PSI
Rear Tire Pressure 40 PSI

A few months ago to correct the wear on the front tires. I drove 8,000 miles on the increased pressure.

The tire store the front tires are wearing evenly now.

 

The pressures on the sidewalls are maximums and are never used as running pressures. You are going to have to start out somewhere as a base and then adjust to your tastes. Too high will affect the ride adversely. Keep in mind that MB specifies lower pressures in front.

 

running Ventus V12's 225/35/19 & 255/35/19 currently set at 32psi Front and 36psi Rear... debating running it a little higher due to the softer sidewalls on the V12's... what have you guys found to be a good PSI range for these specific tires for optimal performance?

 

I have low profile tires. The maximum pressure is 50 PSI. I check with Michelin before adding the additional air to even out the wear on the front tires. The first person I spoke to at Michelin was reading a script. I called another number at Michelin and spoke to someone who was able to answer all the questions about the tire pressure. They always refer to the manufacturer for the correct pressure.

I increased the tire in the rear to be higer then the front because MB recommends the rear tires have a higher pressure.

I can tell the different in the ride and the gas mileage is up a little.