Does a morbidly obese passenger contribute to right tire wear?

I went to Les Schwab yesterday to switch back to AS tires from my studded snow tires. I’ve been commuting to work an average of 330 miles/week with a morbidly obese passenger since last September. 80-85% of my mileage is with this co-worker who weighs around 400 lb (BMI 54). I was told by Les Schwab that my snow tires have 75% left on my left tires, but zip on right. I just had new shocks and rear breaks when I switched to my snow tires mid-December 2012, and my tires were fine (3 months ago). It turns out my AS are also shot. I rotate my tires regularly (front to back, back to front). My front right tire has “the steel belt raising off” and is in danger of a blow out (I’m told). I have a 70,000 mile warranty, but only have 40,000 on my AS tires. Les Schwab will give me 30% off new tires, but it’s still very expensive, plus I’ll need new tires next winter. They told me my uneven tire wear on the right is most likely due to my obese passenger. Is this correct? Has anyone heard of this happening? I have a 2007 Subaru Outback with 900 lb capacity. Thanks for any help!

UN even weght distribution can easily affect tire wear. The 900 lb capacity assumes the weight is properly distributed. So in your case it would be possible, especially if the inflation was low enough, not raised to max allowed and there was much cornering force on that tire. When ever possible, weight should be evenly distributed. I would worry too that this much uneven tire wear my be hard on the awd car if continued. You should have your alignment and wheel balanced checked if not already. Yes, you may need 4 new snow tires and AS if they both exhibit this condition… I would ask my passenger in this situation to help foot the bill beyound what the commute cost is. Back middle seating is a safer place for you, the passenger and the car, which may not be possible. I simpathize with your dilemma. No easy solutions. This all assumes that you are dramatically less in weight.

On the plus side, just think how much more traction you gained in the snow… at least on that side of the car…

“I would ask my passenger in this situation to help foot the bill beyound what the commute cost is.”

I agree with dagosa, but the OP should not be surprised if he/she gets resistance from the obese passenger. After all, when airlines attempt to charge an extra fare for passengers who can’t fit themselves into just one seat, these oversized passengers frequently yell, “discrimination”.

Any logical person would understand that the rest of the world should not have to pay for the extra room/services/wear and tear that a huge person imposes on the service provider, but…logic frequently flies out the window when money is involved.

The answer to your original question is …yes. Morbidly obese drivers/passengers also wear out their seats rapidly. I agree with all the comments and with @VDCdriver in particular.

I don’t usually do this, but I’m going to disagree with the crowd here. That’s a huge difference in tire wear. Many people drive with a normal-sized adult in the passenger seat and a teenager in the back right seat, which starts to approach the weight of your passenger, yet we never hear about extreme wear differences in that case. Similarly, people who put 200 pounds of sand (the rough amount of extra weight on your right side) in the trunk don’t suddenly have the rear tires wearing that much more. I think you should get your alignment checked.


Yes. It’s not just the weight, though that’s a significant part of it. Having that much weight in the right front seat can throw the alignment off, thus the excessive wear on the tire. Years ago a friend of mine had a Nissan Sentra with the same problem, he always wore the left front tire unevenly and prematurely. I finally had to align the car with him in the driver’s seat and that improved things enough until he could buy a bigger car more suited to his size.

@lion9car…I like your attitude. If you disagree with the crowd then disagree. I have a little personal knowledge of this subject though. A good friend of mine owns a large fleet of passenger vans and delivers and picks up train crews from the surrounding states.

He has a driver named Ned (not his real name) who weighs over 400 pounds and is a delightful guy. The crews all know him and consider him a friend. He’s a very safe driver and is always on time which makes him a valuable employee. He does go through driver’s seats pretty fast. The driver’s side front tire also wears out faster than the other 3. He has a dedicated van because of these factors and the fact that his seat is bolted in a different position than normal.

I see your argument but weight centered in the front seat is different than weight distributed between the front and back seat. Extra weight on an axle wheel that does not move right and left like a steered wheel is also different. The wear is there but at a greatly diminished value.

I was the guy who disagreed with this board completely about 15 years ago on the subject of ethanol. Most people had no problem with it at all and I was hammered right and left when I mentioned a “corn lobby.” All these years later and you would be hard pressed to find anyone who does not hate ethanol as much as I did 15 years ago. Hang in there.

We had a large customer who, when it was alignment time, was required to be in his car during the alignment.
Why ?
To be able to set the camber for the maximum amount of time the car would be driven in that manner.

With a lot of today’s cars having independent rear suspension too, you can bet the camber is off in the rear roo.

when constantly hauling, or the majority of time hauling, tire air pressure is extremely important as well.
Usually this comes to light with pickups and other service vehicles that are loaded most of the time.
Now add cars to that list.

I added at the end of my comment, the perhaps embarrassingly,“This all assumes that you are dramatically less in weight” Which IMO would have an effect. My wife found too, that when commuting, if she drove too aggressively to work on a highway system that had “all” too many successive right or left turns, it made a significant difference in tire wear on one side. These could all be factors that exacerbate the problem.

A Subaru with awd, might just be the best sedan equipped to handle the problem safely, but one which may have the highest repair bill later. Maybe pick up passenger so early that you can drive so slowly, he/she might find another means.

@misscleman As a fellow ethanol “hater” too…you are my new hero.

@acemaster has great idea if you could sell your car to obese person, let them deal with the repairs and you ride…for free for a while.

Yes, your passenger makes a difference in the entire wear, as everyone else has said.

However that does not mean you should ignore other factors that contribute to uneven wear. Have your alignment checked, make sure everything on the chassis is in good operating order, and monitor your tire pressures.

As regards the cost issue; anyone who mooches permanent daily transportation from another without offering some method of sharing the cost is not worthy of the ride. Simply tell your coworker that you’re happy to do all the driving but he/she needs to share the cost.

So, how is the gas milage?

Thanks, it’s a co-worker and I’m stuck commuting with him. My gas mileage is less, But I do get reinbursed from work. I have my tires aligned every time I rotate my tires (3000-5000 miles). I check my tire pressure routinely and commute on a fairly flat, straight highway. My tire pressure warning light flicks on and off when he’s in the car and doesn’t when he’s not riding with me. I’m a third his size. So back middle seat? Is that the safest place for him?

"So back middle seat? Is that the safest place for him? "
That’s the safest for everyone, including the car. If the passenger can’t fit in the middle, you have the option of “rotating” from side to side or at least, diagonally opposite you. but the back for sure !! I would also make sure tires are pumped to maximum allowable air pressure. If he is in the back middle, there should be NO problems handing the weight though it might not be as easy for you or him with the reduced leg room. I would definitely give it a try. 400 lbs in the back if balanced is no more then a couple of mid size commuters, deserving though of MORE air pressure…can’t stress that enough. I would use max pressure on the tire unless the manual gives you a max pressure option. The standard on door jam may not be complete enough for your situation…some will disagree I know on that point.

If work reimburses you, I definitely would take the bill along with statements from mechanics concerning the tires and suspension work and ask for help. Also, gas reimbursement alone for one person is NOT ENOUGH IMO. A higher per miles fee then their usual is in order,you are carrying TWO people. Asking double regular gas fee is NOT out of line…BTW, if your Tire Pressure monitoring devise is flickering and it uses the rotational difference to monitor them, It would definitely indicate you need more pressure and it’s not good for AWD over time. If just higher in all tires doesn’t keep them from flickering, perhaps max just in the rear if weight ends up there…experiment. I do this normally the tire with trucks and heavy loads on long trips.

Thank you again, good advice. One last question, is there a point where weight plays into the efficacy of seat belts? My front passenger seat was completely flattened out after the first 3-weeks of commuting. Is there a weight where car seats and seat belts won’t work due to obesity?

You have a Subaru so maintaining an even tire wear is critical and rotations are a must, but I think you are rotating them too frequently and you have to do a cross rotation on two of the tires each time. They way yours are wearing now can do damage to your center differential.

I think you are doing way too many alignments and not having them done right. Cars don’t go out of alignment that often. You need to get a tire tread depth gauge, a cheap one for about $3 is all you need, then check the tread depth on your tires about once a month. Rotate the tires when the difference between the deepest and shallowest treads is 2/32" and not before. Also check the treads from the inside to the outside of each tire and if it is not wearing evenly, then you make an adjustment.

Rotating too often masks any suspension problems. Doing it less frequently will help discover any problems and correct them. Front tires should cross going to the back, rear tires stay on the same side going to the front. You should only do 4 rotations for the life of the tires.

If you find the tread on one side of the tire worn more than the other side, then you need an alignment. If the tread is worn on the outsides of the tire more than the center, then you need to increase your air pressure. If the center treads are worn more, then you need less air pressure. Because of the extra weight you carry all the time, I would guess that you need a little more air pressure.

Something else that might help is going to the next size larger tire. For example, if you currently have 225/60R16 tires, you could go up to a 235/60R16 tire or 225/65R16 and it will increase the carrying capacity of your vehicle.

I’m with lion9car on this issue.

Consider: you have a right-seat passenger that weighs around as much as two adults. So, the weight asymmetry is roughly equivalent to an average-sized adult driving alone.

And, from that, we have a LF snow tire at “75% wear remaining” and a RF showing cords. I would argue that a 200#ish weight disparity, L-R, is a vastly insufficient explanation for the observed phenomena.

Also, remember that we take all OPs “as they come” and have to take complaints as objective; however, the mere fact that OP went through the time and effort to calculate the BMI* of his or her passenger says a lot, I feel, about OP’s objectivity W/R/T obesity. (Consider especially that BMI is wholly irrelevant to the car–it cares not if it’s carrying a short, chubby person, or a very tall one.)

I would argue that the likely explanation is that some unrelated problem is causing uneven wear, likely modestly exacerbated by weight distribution. The OP, who likely harbors some level of antipathy for obesity in general, is quick to blame that particular boogeyman for his or her problem here.

Given that efforts to make rider pay a disproportionate share of the costs would likely be taken poorly by the hefty passenger, I would advise the OP to just stop carpooling–no reason given. It probably won’t be taken any worse than “pay double, big man” would. I would then encourage OP to search for the root cause of 3X the tire wear on the RF, 'cause I doubt it’s this.

  • BMI: A wholly inadequate tool for obesity, as any tool that suggests you “get healthier” when you lop off a limb must be. In fact, the originator of the metric cautioned specifically against its use on an individual level, but only to use it to compare populations of otherwise-heterogeneous people.

It is in use medically mostly because most MDs are too lazy to bother with skinfold and/or circumference tests in a case where patient compliance is low regardless.

Thanks @dagosa…I became an “ethanol hater” the minute I got the repair bill for my wife’s '85 Cadillac Fleetwood FWD. The ethanol had eaten all the rubber components out of the TBI system and had plugged up the fuel filter. The thing was…there was a big push for ethanol in the area and we were told time and time again that ethanol would not harm our vehicles. Repair shops, including farm equipment shops, in the area (Northern KY/Southern Ohio) were booked solid for months after ethanol was added to gasoline.

If there is it’ll be in your owner’s manual.

Re: obesity and seatbelt concerns, I know that some manufacturers offer free seatbelt extensions for owners woh have people too obese to properly attach seatbelts. I got free ones for omy car. Ask your dealer’s parts department. It may be a federal requirement, I really don;t know.