Increasing Tire Pressure on Rears!?!

[Carolina Rauder]

I see that alot of members increase the tire pressure in the rear from 35psi(recommended) to 38psi or even 40psi, to prevent premature center tread wear. Correct me if I'm wrong but I thought increasing the tire pressure only exposed the center of the tire more to the road????

When riding OE tires....

[KillJoy]

I run 38 on the Rear.

Burnouts still effect them :D

KillJoy

[Joe Walsh]

I see that alot of members increase the tire pressure in the rear from 35psi(recommended) to 38psi or even 40psi, to prevent premature center tread wear. Correct me if I'm wrong but I thought increasing the tire pressure only exposed the center of the tire more to the road????

When riding OE tires....

I thought the exact same thing, but apparently the Marauder BFG KDWS P245/50-18 rear tires contradict all normal PSI schools of thought.
More pressure saves the center from excess wear.
There is an old thread where this was discussed at length and someone knowledgeable on the subject gave a good explanation as to why this is true.

[duhtroll]

This is because the OEM rears have a weak sidewall, allowing center expansion at highway speeds. There have been several threads in the archives about this.

I believe the KDW2s don't have this problem.

[Marauderman]

I see that alot of members increase the tire pressure in the rear from 35psi(recommended) to 38psi or even 40psi, to prevent premature center tread wear. Correct me if I'm wrong but I thought increasing the tire pressure only exposed the center of the tire more to the road????

When riding OE tires....

Being a Carolind Marauder Memeber--....its easy to spot your post ................but to answer your Q///////////\
Your right-normally---like what has been mentioned--it depends on alot of things----you do not say your mileage or type tire--we assume your saying the OEM's==Right?--In any case--normally yes--Changing type tire changes the whole pressure thingy-----its been proven--the car is almost 5 years old for some of us--not all--mine is only 4 last Nov.'06 for the record--:lol:

[Carolina Rauder]

Yes I'm running the OEM's KDWS. I'm wanting to know the best pressure for front and rear????

[ctrlraven]

I have 255/55-18 kdw2 on my rear and I run 36psi.

[Marauderman]

Yes I'm running the OEM's KDWS. I'm wanting to know the best pressure for front and rear????

Honestly--I have not used those type tires--many have here on the board---Hopefully one will post up heer and tell you who has used those tires--but in the meantinme--I would use 34/35 back----lets see who helps you out here--I switched from the OEM's to the NITTOS --and still with them--..so really can't help you out that much---I will call some others to see if they can post up about this--mean while--the "search" function....if you have time ..it can be very helpful--if it hits on what your looking for---Tom

BTW--Where in Fayett?????

[jim geary]

I used 35lbs both front and rear.Never had a problem. Just put on Nitto's at
26,400 and still had plenty of tread left on the old ones. BFG's that is.

[warren]

I run KDWS's
38psi Front
42psi Rear --- due to MM torque our rear centers wear faster/ the higher
rear pressure will combat this. Also use nitrogen air for lower heat buildup.
Visited a Big O tire shop out here and they had newest hunter equip.
Balanced, switched side to side for free today and
the nitrogen change over was only 5.00 per tire.

Warren

[Bluerauder]

I see that alot of members increase the tire pressure in the rear from 35psi(recommended) to 38psi or even 40psi, to prevent premature center tread wear. Correct me if I'm wrong but I thought increasing the tire pressure only exposed the center of the tire more to the road????...

I am running 38 psi rears and 35 psi fronts on the OEM KDWS.

This was posted by TireNerd2 on the BFG site back in February 2005 when this was discussed then ....



*RE: RE: ???Center wear on rear KDWS's
by TireNerd2
February 23, 2005 8:28PM


Nope. The KDWS does not have a softer compound in the middle of the tread. The KDWS uses a single tread compound accross the entire face of the tread. Center rib tread wear can be caused by many things. However, take it from me as a Tire Designer (6 years) and Ex-Test Driver for BFG (6 years), rear wheel drive, high horsepower, and high torque applications that exhibit accelerated center rib wear usually benefit from INCREASING cold inflation pressures. Now I know absolutely everyone in the public domain will tell you accelerated center rib wear is caused by over inflation, but believe me it's also caused by under inflation on the 'driven axle'. So in a sense both situations lead to center rib wear depending on whether the axle is being driven or not i.e. whether the tire experiences an engine driving torque or not. Adding some air to the rear axle of the Marauder in this example will stabilize the contact patch and help it maintain its shape better by keeping more rubber on the road under a driving torque. Essentially, if a driven axle tire is under inflated when it experiences a high driving torque, the leading edge of the contact patch is forced into the road and the trailing edge of the contact pathch is 'pealed' up (you can watch dragster tires do this when they stage at the line). When this happens the unit contact pressures increase at the leading edge of the contact patch, which increases contact stresses and accelerates wear. The centerline of the contact patch just happens to be the location of highest contact pressures and so exhibits the highest wear rate. I know this may sound odd - and I know maybe counter to what you've heard BUT adding air reduces center rib wear in higher horsepower applications by stabilizing the contact patch shape. Keep in mind O.E. inflation pressures are a comprise by the manufacturer for ride and handling and not optimized for tire wear life. So add at least 5 to 7 psi cold to the rear axle tires and the KDWS wear life should increase.

[FordNut]

Sounds bass-ackwards, but it works. Run them at 40

[walela1]

Today @ Ron's Tire and Wheel in N. Hollywood Ca. it was recommended to me to run 3lbs higher in the front to combat the edge wear, and 3lbs in the rear less to fight the center wear.

I had 29,795K on the fronts yesterday when I had to have them replaced due to excessive inner ( down to steel belts in some places,) edge wear as well as some outer edge as well.

Today I had the front end aligned to Carfixers alignment specs,at the dealership, cost was $85.00@ the dealership for an hours worth of work. Hope it cures the problem.

I had to replace the rears @ much lower mileage. Both BFG and the dealership say the mileage on the fronts was outstanding. BFG said they only rate the tires mileage wise for 10-20 k. But they may compensate me some way.

Best,
Walela:banana:

[FordNut]

Today @ Ron's Tire and Wheel in N. Hollywood Ca. it was recommended to me to run 3lbs higher in the front to combat the edge wear, and 3lbs in the rear less to fight the center wear.

I had 29,795K on the fronts yesterday when I had to have them replaced due to excessive inner ( down to steel belts in some places,) edge wear as well as some outer edge as well.

Today I had the front end aligned to Carfixers alignment specs,at the dealership, cost was $85.00@ the dealership for an hours worth of work. Hope it cures the problem.

I had to replace the rears @ much lower mileage. Both BFG and the dealership say the mileage on the fronts was outstanding. BFG said they only rate the tires mileage wise for 10-20 k. But they may compensate me some way.

Best,
Walela:banana:

The fronts wore due to alignment. Next set will last a lot longer since you fixed it.

The replacement rears will wear out even quicker, wearing in the middle, with lower pressure. Been there, done that. Run 40. Or buy stock in BFG.

[MENINBLK]

Yes I'm running the OEM's KDWS. I'm wanting to know the best pressure for front and rear????

The BEST tire pressure for any tire is 90% of MAX PSI as stated on its sidewall.
This allows the tire to do its thing as it was designed to do.
This is why the KDWS requires 38-40 PSI for even wear.
MAX PSI is 44 psi.

Automotive Manufacturers know absolutely NOTHING about tire pressures.

[MENINBLK]

This is because the OEM rears have a weak sidewall, allowing center expansion at highway speeds. There have been several threads in the archives about this.

I believe the KDW2s don't have this problem.

The sidewalls are not the problem.
The KDWS does NOT have sidewall problems.

Read the post that I made that explains the problem
so you understand the theory.

[duhtroll]

Were this absolutely true, many tires on many vehicles would have the same problem as most people/places do not inflate as you suggest. Since this excessive center wear is a rarity experienced with the KDWS, I'm sticking with the opinion of those who did this analysis a few years back.

Of course most of us switched tires right afterward, because the KDWS is an inferior tire to the KDW2.

Regardless of the reason, all inflation procedure included, the treadwear longevity just ain't there.


The sidewalls are not the problem.
The KDWS does NOT have sidewall problems.

Read the post that I made that explains the problem
so you understand the theory.

[RF Overlord]

Yes I'm running the OEM's KDWS. I'm wanting to know the best pressure for front and rear????

Like you, I didn't believe that increasing the tire pressure would make the centre tread wear problem better, but I followed the advice and increased my rear pressure to 38. Lo and behold, my rear tires are now wearing much more evenly.

I'm not sure there's one "best" pressure. Less pressure may give a better highway ride, but reduce handling. More pressure may give better tread wear, but make the ride harsh. It will always be a compromise. It seems that running something in the neighbourhood of 35-36 in the front and 38-40 in the rear yields a reasonable mix of decent ride, handling and tread wear.

Interesting side note that many may not realise: the "recommended" tire pressure for '03s was 32 F&R, but was increased to 35 F&R for '04. Same tire, same vehicle weight, same suspension, same everything. Maybe Ford realised that 32 was too low in the first place?

[BLACKMARAUDER04]

I Run 35/35 On The Oem Kdws'. The Rears Last 16-20m, The Fronts About 35m Miles.

[Dr Caleb]

The Rears Last 16-20m, The Fronts About 35m Miles.

Yea, if I ever get supercharged my back tires will also last about 15 minutes, tops.


Just finally ordered my first set of new rear BFG's in the stock size. 4 years, 30,000km and the centres are gone! I did boos them up to 40psi when the problem was first discussed, and I had 15,000 on them already. So the damage was done.

[MENINBLK]

Were this absolutely true, many tires on many vehicles would have the same problem as most people/places do not inflate as you suggest.

In Fact...They Do...

Walking through a parking lot, look at only CARS, not SUVs, Crossovers,
or anything larger than your Marauder.
If you look at the sidewalls of most CONVENTIONAL tires, MAX PSI is usually stated as 35 PSI.
35 PSI x 90% = 31.5 PSI (32 PSI) which is the pressure most automotive manufacturers recommend.
The only tires that are usually the exception are HIGH PERFORMANCE tires.

Also,the explanation I gave is directly from BF Goodrich.
During that time, BF Goodrich had a Customer Forum which since then, has been taken down.
Many of us are familiar with it because we would go there and SCREAM
when the rear tires were in a backorder status at most tire dealers.
The center wear pattern has nothing to do with weak sidewalls, it is just physics.
If you understand the forces that play a role in the wear of the tire,
and what forces need to be created so that the tire footprint remains
in contact with the road in order to wear evenly, you would also understand
why a higher pressure is necessary and it does not take away from the tire's performance.

The KDWS is also NOT an inferior tire to the KDW2. They are two different tire designs.
The KDWS is an ALL SEASON tire, while the KDW2 is a Higher Performance Summer Tire.
Anyone who lives in the snow belt who tries to drive on KDW2 tires
in late fall/early spring will know the difference between the two tires.
For those who live in the warmer climates,
the KDW2 IS a better choice for a year round performance tire.
With EITHER tire, the best thing to do for Winter driving is to swap in
a set of Winter SNOW tires for the duration of the winter.