Tire pressure

    We just installed new tires on our Jetta where this is just an observation in which I thought would provide some interesting discussion. If you go online to question what tire pressure is best for your vehicle, the response you will find is to follow the vehicle manufacturers recommendations on the door jamb, fuel filler door, etc. With this in mind, whenever we have taken our passenger vehicles in to be serviced by a tire dealer, we have yet to have them inflate the tires to this "recommended" pressure. Why would you say this is?

    Bill

    Laziness I think, or they assume.


    I really like Discount Tires, free fixes/rotation and they typically have very competitive prices, if not the best. However, whenever we have anything done on our cars, they never put in 36 lbs of air, almost always 30 - 32, and that triggers the dummy TPMS lights, if not right then, soon after.


    I always have to hit them with a bit of air at the house.

    One thing to be aware of is that the maximum pressure listed on the tire will give you 100% of the rated load capacity for that tire. If you air your tires to 90% of the maximum pressure, you will get 90% of the rated load capacity, etc. So if you want to be sure to meet your load requirements, divide the manufacturer's recommended pressure by the OEM tire's maximum pressure, then multiply that percentage by the rated load capacity for that tire to determine the load per tire that the manufacturer is recommending. You can do the same with your replacement tire to make sure you are meeting the load requirement. If the load capacity of the replacement tire is similar to the OEM tire, using the manufacturer's recommendation should work fine.


    I typically run my truck and trailers at 90% of maximum pressure to handle the heavy loads I haul, but still have a safety margin. I may be sacrificing some comfort as far as ride smoothness but it's a truck and you don't buy a truck above a half ton for comfort.


    As far as your question why the tire dealers don't use the recommended pressure, my thought is that everything they do is with liability in mind and it might be that they have a range that supposedly prevents litigation.


    By the way, where is SSREAPER ? He'd have some insight on this.

    Remember folks - this isn't a rehearsal, this is The Show!8)

    Over inflated tires will wear out the center of the tire first...

    You the owner have to find the happy medium....And also trike tires have a tendency to balloon out at highway speeds..

    Which will also add to center thread wear...

    Some times a Cigar is just a Cigar.......

    Quote from Bigdog

    Under inflated tires wear out on the outsides of the tires....job security...

    They can also tell you you need an alignment....up sell...



    It’s certainly not for your best interest...

    Personally, if a tire dealer needed an excuse to recommend under-inflating the tires that they install, all they would need to do is use some of the vehicle manufacturers recommendations? For example, Volkswagen recommends inflating the 195/65R15 tires on the Jetta to 26 lbs front and rear, I do not think I personally could recommend this information?


    Also, I have yet to have any reputable tire dealer recommend unnecessary service, where are you taking your vehicles to to get tire service so we can avoid them, Bigdog?


    To make this thread relevant to the SlingShot, I must confess that I have found using Polaris' recommendations for tire inflation to be pretty darn close where I am comfortable using them.


    Bill

    The tire pressure to me has always been determined by #1- tire brand #2 - type of tire #3 -rim width #4 weight of the vehicle and #5 and last but not necessarily least the type of driving. Since 1957 with my first car I have always set my tire pressures according to the actual wear pattern across the tire tread (you know the piece that hits the pavement) Even when changing tire brands on the same vehicle the actual tire pressure that you will be running will be different. That is if you keep up with the tread wear

    OK, back to my original question where if you research on the Internet, or call and ask a tire dealer, you can bet money that they will advise you to use the tire pressure as recommended by the vehicle manufacturer. But, when it comes down to actual practice, very few tire dealers actually return your vehicle with the tires at these specifications, in other words, why do tire manufacturers and dealers advise one thing, and then go against their own advice when it comes to checking, or installing, your tires?


    Bill

    At the risk of this topic turning catastrophic......


    While we were having the 3 wheel alignment discussion one of the important factors was making sure your tire pressure was what Polaris recommended. Which is pretty low. They Recommended only Kenda tires....max pressure on a Kenda is 51 PSI


    I’ve been dealing with my tire guy since 1973. That’s thousands of dollars worth of tires....I totally trust them to not screw me....that said....the guys that do the actual tire work.....are usually young guys. They will put in as much or as little air that you tell them ....if I tell them I’m hauling an extra 1000 pounds they increase the tire pressure. I normally buy the heavy duty sidewall tires.....


    So the SS being really light riding on car tires not technically motorcycle tires....Polaris obviously feels less air is better for handling, traction, tire wear or whatever.


    Too much air affects the alignment numbers...


    As to tire guys I don’t trust....it’s the national chain stores that work on commission to keep their jobs.....they want your tires to wear out every month...girls and elderly people get a different price than guys.

    The tire pressure to me has always been determined by #1- tire brand #2 - type of tire #3 -rim width #4 weight of the vehicle and #5 and last but not necessarily least the type of driving. Since 1957 with my first car I have always set my tire pressures according to the actual wear pattern across the tire tread (you know the piece that hits the pavement) Even when changing tire brands on the same vehicle the actual tire pressure that you will be running will be different. That is if you keep up with the tread wear

    Quote from wjfyfe

    OK, back to my original question where if you research on the Internet, or call and ask a tire dealer, you can bet money that they will advise you to use the tire pressure as recommended by the vehicle manufacturer. But, when it comes down to actual practice, very few tire dealers actually return your vehicle with the tires at these specifications, in other words, why do tire manufacturers and dealers advise one thing, and then go against their own advice when it comes to checking, or installing, your tires?


    Bill

    One is the tire gauges are not accurate especially the sliding scale one's

    I am no tire expert, but here is my thinking on the subject.


    Tire manufactures print the maximum safe pressure on the tire. I assume that this is what their testing shows to be the highest that allows for expansion from heat and will be safe and within operating limits. - - - this is a number that is based only on the tires ability and not what vehicle the tire might be installed on.


    Now, the pressure that the vehicle manufacture puts on the door, this number is a number that is optimized specifically for the tires on this vehicle it takes into account the weight and weight distribution of the vehicle. I assume this number is geared to give a compromise between road performance and tire wear. We as end users will be best served if we use this as a base and then adjust for how we are actually using our vehicles


    To me it seems reasonable to assume that on a light weight vehicle like our slingshots that a lower pressure would be required/desirable than the pressure you would want on a heavier vehicle using the same tires

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    You really want to try something? Try about 80 PSI in your car/truck tires and drive it down the road. It is like bouncing a basket ball. I did not do this, I had a dealer install brand new tires, I wondered what in the hell was going on while I was driving down the road. So when I got home I checked the tire pressure on all 4 tires and they were 80 PSI, it makes for a very interesting ride.

    Quote from FunCycle

    You really want to try something? Try about 80 PSI in your car/truck tires and drive it down the road. It is like bouncing a basket ball. I did not do this, I had a dealer install brand new tires, I wondered what in the hell was going on while I was driving down the road. So when I got home I checked the tire pressure on all 4 tires and they were 80 PSI, it makes for a very interesting ride.

    They put the 80 psi to set the beads on the rim....And then forgot to bring it back down to Spec......

    Some times a Cigar is just a Cigar.......

    It’s recommended that tire pressure be taken while the tire is cold.....meaning you didn’t drive 20 miles already because the air heats up and expands making the pressure higher....then you don’t get an actual reading. If it’s heated up any reading is at best an estimate.

    Last night was the coldest we have recorded. Last night was also a full moon. Last night was also a total eclipse of the moon....


    I checked my tires under all those conditions and I should now be good to go until I replace the tires. :thumbsup:

    Slingshot Flyer! Well, of course it's red... :REDSS:

    I use LT tires because the dry curb weight on my truck is 6,000 lbs. So the fronts are at 55 psi and the backs are at 75-80, per guidance on the door sticker. Never had bad wear patterns.


    Now, on the Sling, I'm 8-10 psi under recommended pressure.

    No Kidding. That was the highest that I have ever found the tire pressure left at. Most the time it is around 60 psi. I do not think that I have ever found them at the correct pressure. I check the pressures as soon as I get home every time that someone else checks the pressure