Is it OK to fill tires to max psi?

Written By Riaan Gvp

Table of Contents Show

Why You Should Not Fill Your Tire to The Maximum PSI?
Why Do Over Inflated Tires Cause a Bumpy Ride?
Why can overinflated tires cause bad handling or unsafe breaking?
Why are you more likely to receive a puncture with higher levels of PSI in your tires?
What Should Your Tire Pressures Be Kept At?
What is the maximum safe tire pressure you can use?
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Is 40 psi too much for tires?
Is it OK to go over PSI on tires?

Last Updated November 11, 2022

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The maximum safe pressure for your tires is displayed on the sidewall of the tire. However, the recommended tire pressure is vehicle-specific and can be found in two main areas. Firstly, the recommended tire pressure will always be located in the user manual. Secondly, most vehicles have the recommended tire pressure listed on the door jamb sticker.

You should not fill your tires to maximum tire pressure, which is displayed on the sidewall of the tire. Among other things, this can lead to structural failure of the tire. Such a failure will most likely result in a blowout. Unless you are off-roading, you should try to keep your tires at your vehicle’s recommended tire pressures.

Why You Should Not Fill Your Tire to The Maximum PSI?

Filling your tires to maximum pressure is a dangerous game to play. The main reason is the risk of a blowout. Even coming close to the thresh hold of maximum tire pressure is dangerous. As the tires heat up while being used, the pressure inside the tire increases. This is caused by a process is called thermal expansion.

As the tire experiences thermal expansion, the pressures inside the tire can build up way past the maximum PSI. Eventually, this will pop the tire just like an overinflated balloon, which we call, a blowout. The blowout is the most dangerous problem caused by over-inflation of the tire, however; there are a few other issues that can not only cause great discomfort but can also lead to accidents.

Why Do Over Inflated Tires Cause a Bumpy Ride?

Some of us tend to forget that the tire is a part of the vehicle’s suspension system. The air inside the tire acts as a cushion that absorbs impacts from an uneven road surface. Many people that use extremely low-profile tires suffer from bent rims. When a low-profile tire hits a pothole there isn’t enough cushion to protect the rim.

This can be offset by the tire if its sidewall is extremely rigid, but the occupants of the vehicles will feel every little bump. This can also be your experience if you over-inflate your tire. If the PSI is too high in the tire it cannot give way to cushion the blow from a bump or pothole.

Furthermore, because of the high air pressure in the tire, the side wall is held rigid, preventing it from flexing. This in itself can cause a blowout. Because the tire cannot flex or bend, the force and mass of the vehicle bearing down on the edge of a pothole, or a bump causes the rubber of the tire to crack or tear.

Why can overinflated tires cause bad handling or unsafe breaking?

Your tire is the only thing keeping you on the road and going in the direction you want to. It does this with surface tension The more of the tire that is touching the road surface, the better your traction will be. Unfortunately, an overinflated tire bulges out on the centerline.

With overinflated tires, you only have a thin centerline of rubber keeping you attached to the road. This translates to worse handling and less stopping power. It also means that over time the tires will have increased wear down the center, which will dramatically reduce the life span of your tires.

Why are you more likely to receive a puncture with higher levels of PSI in your tires?

For the same reason, you are going to feel every bump and dip, you are more likely to get a puncture. Due to the higher pressure, the tire is unable to give way. This makes it easy for a puncture to occur. You can demonstrate this by trying to pop and semi-inflated balloon and a fully inflated balloon. The fully inflated balloon will pop long before the semi-inflated balloon does.

What Should Your Tire Pressures Be Kept At?

The safe bet with tire pressure is to stick to the recommended PSI values found on the door jamb sticker. However, there can be some exceptions to this rule. When the manufacturer sets these values, they have a certain tire in mind. Let’s say the tire the manufacturer is working with has a maximum PSI of 35 and they recommend that you use 32 PSI for the fronts and 28 PSI for the rears.

By the time you need new tires, you buy the ones you like, and it turns out their maximum PSI is 44. No big deal, right? You are still well within the maximum limit. Wrong, 32 PSI on a tire with a max of 35PSI will not handle the same on a tire with a max of 44 PSI. The correct pressures for a tire with a max of 44PSI will most likely be 41PSI on the fronts and 36 PSI on the rears.

Additionally, pickup trucks will often have much higher PSI recommendations for the rear than the fronts. This is done so they can support weight in the back or support the weight of a trailer. However, when there is no load, the back can bounce around quite a bit, especially on dirt or gravel roads. For this reason, it is not a bad idea to decrease the PSI from say 72 PSI to 50 PSI. Just make sure you readjust the pressures before adding a load again.

What is the maximum safe tire pressure you can use?

As long as you stay within the recommended range the manufacture provides, you should be good. However, if you need to increase the PSI because you are towing or moving something heavy, or you simply don’t have the recommended specification, you can use the maximum PSI as a rough guide.

A good rule of thumb to use is 75% of the total maximum pressure displayed on the tire. For a tire of 50PSI, the more pressure you want to safely use is 37.5PSI. This number is easy to get, just take the maximum PSI (50) and times it by .75. You could go as high as 90% of the maximum but at the end of the day, you will want to stay as close to the recommended manufacture’s values as possible.

Conclusion

Filling your tires to the maximum tire pressure is a bad idea. Not only will it give you a myriad of issues such as an uncomfortable ride and bad tire degradation, but it can also be extremely dangerous. The main thing you want to do is match your vehicle manufacturer’s PSI recommendations as closely as possible. The best time to check and adjust your tire’s PSI is early in the morning while they are still cold.

Recently Published Guides

Is 40 psi too much for tires?

Specifically, the level of 40 psi can be suitable for passenger cars or sports cars. But this is too high for small cars with a recommendation below 35 psi, while 40 psi is too low for large trucks. The recommended level for the tires of famous sports cars and passenger cars is between 32 -40 psi.

Is it OK to go over PSI on tires?

So, when filling your tires, the recommended tire pressure is the best compromise between handling, comfort, fuel economy and safety. But it's certainly fine to go over the recommended inflation by a psi or two. And going over is always better than going under.