Tire Blowout at 70 MPH

[Der]

The Rivian is fine. We had 3 adults in the truck and three suitcases. I had a 3 guitars in the gear tunnel, not a lot of extra weight. I check the tire pressure fairly regularly- several times a day on a road trip. I firmly believe that it’s unreasonable for a tire to blow out in this scenario. Whatever happens from here I’m still in total lust with my truck.

Also FYI- this was a classic blowout. Rim to rim gash. First time it ever happened to me.

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[Glembi2]

Blowouts at speed are scary. I applaud @Der for keeping control of the truck.

 

[RivianRunner]

50 PSI while driving

Why were you driving on under-inflated tires, especially on fast roads, loaded for a multi-day trip?

It makes no sense.

 

[RivianRunner]

Was getting to 57 psi while driving so I was concerned about over pressurization

The max pressure listed on the sidewall is a cold inflation pressure. The tires are designed to handle hot pressures well in excess of the maximum cold inflation pressures. Your concern of over-pressurization was not valid.

 

[azbill]

Glad you're ok. Something similar happened to me within 2 weeks of delivery. Looked like a piece of shrapnel. Replaced at Discount Tire. Then a couple of weeks later got a nail. Discount tire offers a road hazard warranty for about $450. I got that.

I bought 5 new tires on Tire Rack and had them delivered to Discount for mounting. Tire Rack gave me two years road hazard for free. Cost to mount them was $110.

Discount is basically charging the cost of a new tire for the warranty, they used to be much more reasonable.

 

[emoore]

Why were you driving on under-inflated tires, especially on fast roads, loaded for a multi-day trip?

It makes no sense.

That’s not under inflated. Mine are 48 psi cold and 50 psi hot.

 

[RivianRunner]

That’s not under inflated. Mine are 48 psi cold and 50 psi hot.

Manufacturers never give a hot pressure recommendation.

Normal pressure rise from stone cold to mid-day highway pressures is more typically 4-5 psi. Maybe you are unaware that cold pressure is first thing in the morning, without having driven at all. Even a two mile drive or sitting in the morning sun will bring the pressure above the cold pressure. It could be that your tire pressure gauge reads a couple psi high too. The tires are designed to be driven hot at pressures well above the maximum cold psi inflation pressure. Correct tire pressure is essential to avoid blowouts. It's OK if the hot tire pressure rises 6 psi above the maximum cold inflation pressure, they are designed to do exactly that.

If Rivian equipped the R1T with tires that have a recommended pressure only 2 psi below the maximum pressure rating, I think that's irresponsible and requires even closer monitoring of the pressures when travelling on highways with a load (and three adults and luggage qualifies in an R1T) in order to make sure the tires don't fall below the recommended cold psi inflation pressure. For example, if the tires read 50 psi in the mid-day sun while travelling on the highway with a load, you are most certainly below the manufacturers recommended cold inflation pressure. I would always err on the high side in such situations if you want to avoid blowouts.

 

[RivianRunner]

I should add that with 7800 miles on the tires, it's possible the tires were already compromised by having driven on the highway during hot weather with one or more under-inflated tires. That can permanently weaken the tire and make it more susceptible to heat induced blowouts on future trips.

Tires have the hardest job of any part of the vehicle and need to be treated with respect. Especially on a vehicle as heavy as an R1T.

 

[Hillbilly]

Left Atlanta in late June for Maine, everything went great on the ride up north. Charging was super easy all the way and my truck performed beautifully. Ten days later on the way home I had a sudden right rear tire blowout on I-81, which was startling and a bit scary. My wife had insisted on buying a spare tire prior to the trip so naturally I thanked her profusely and the n changed the tire. Relatively easy.
The tires only had 7800 miles on them and I didn’t hit anything damaging. The incident recorder caught the whole thing. I’ve got a SC appt in a coupe days to have the tire assessed and the others rotated. I’m expecting to realize some sort of warranty action. I’ll post an update

I would bet you hit something. Good thing you had a spare.

 

[emoore]

Manufacturers never give a hot pressure recommendation.

Normal pressure rise from stone cold to mid-day highway pressures is more typically 4-5 psi. Maybe you are unaware that cold pressure is first thing in the morning, without having driven at all. Even a two mile drive or sitting in the morning sun will bring the pressure above the cold pressure. It could be that your tire pressure gauge reads a couple psi high too. The tires are designed to be driven hot at pressures well above the maximum cold psi inflation pressure. Correct tire pressure is essential to avoid blowouts. It's OK if the hot tire pressure rises 6 psi above the maximum cold inflation pressure, they are designed to do exactly that.

If Rivian equipped the R1T with tires that have a recommended pressure only 2 psi below the maximum pressure rating, I think that's irresponsible and requires even closer monitoring of the pressures when travelling on highways with a load (and three adults and luggage qualifies in an R1T) in order to make sure the tires don't fall below the recommended cold psi inflation pressure. For example, if the tires read 50 psi in the mid-day sun while travelling on the highway with a load, you are most certainly below the manufacturers recommended cold inflation pressure. I would always err on the high side in such situations if you want to avoid blowouts.

50 psi hot pressure isnt low tire pressure. Not for a cold tire pressure of 48. I’m sure in hot locations it would get to 52-54. Not sure why you are saying 50 psi is low.

 

[RivianRunner]

50 psi hot pressure isnt low tire pressure. Not for a cold tire pressure of 48. I’m sure in hot locations it would get to 52-54. Not sure why you are saying 50 psi is low.

I'm saying 50 psi is low because they were doing extended highway travel in hot weather with a load. The pressure should have read a bare minimum of 52 psi, I would have been more comfortable with 54 psi if it was sunny and warm and I was doing extended highway driving with three adults and luggage in a heavy vehicle like a Rivian.

The problem is that tires build heat simply from driving and that heat is in addition to the heat of the pavement and the heat of the sun shining directly on the black tires. The lower the pressure, the more heat that creates. The higher the load, the more heat that creates, the faster the speed, the more heat that creates.

Tires can only handle so much heat before they fail.

That's why the load rating of a tire goes up with increasing pressure, there is less heat generated at higher pressures. On a hot day, low pressures, a big load and high speeds on a hot highway is a dangerous combination. It can be made worse if the pressure varies between tires on the same differential (because the slightly different tire diameters causes the differential to grind away creating more work for the tires to do, which increases heat buildup).

It's also possible the tire was defective, causing it to build more heat than it should, but that would be pretty difficult to determine without enlisting specialists. And I'm not talking the kind of "specialist" employed by tire stores.

 

[emoore]

I'm saying 50 psi is low because they were doing extended highway travel in hot weather with a load. The pressure should have read a bare minimum of 52 psi, I would have been more comfortable with 54 psi if it was sunny and warm and I was doing extended highway driving with three adults and luggage in a heavy vehicle like a Rivian.

The problem is that tires build heat simply from driving and that heat is in addition to the heat of the pavement and the heat of the sun shining directly on the black tires. The lower the pressure, the more heat that creates. The higher the load, the more heat that creates, the faster the speed, the more heat that creates.

Tires can only handle so much heat before they fail.

That's why the load rating of a tire goes up with increasing pressure, there is less heat generated at higher pressures. On a hot day, low pressures, a big load and high speeds on a hot highway is a dangerous combination. It can be made worse if the pressure varies between tires on the same differential (because the slightly different tire diameters causes the differential to grind away creating more work for the tires to do, which increases heat buildup).

It's also possible the tire was defective, causing it to build more heat than it should, but that would be pretty difficult to determine without enlisting specialists. And I'm not talking the kind of "specialist" employed by tire stores.

2-4 psi is probably within the accuracy of the tpms. You cant infer that they were under inflated with a 2 psi difference.

 

[RivianRunner]

2-4 psi is probably within the accuracy of the tpms. You cant infer that they were under inflated with a 2 psi difference.

I have direct experience with about 60 tpms pressure sensors. Each one read within 1 psi of the true pressure. I'm not saying there can't be outliers, but the TPMS sensors should never be used to set the cold psi anyway. Always use a quality tire pressure gauge to set cold pressure and ensure it's periodically checked against other quality gauges for accuracy. The reason TPMS sensors should not be used as the primary pressure reference is because it's always better to use the same gauge on every tire. Consider what happens if one sensor reads 1 psi high and the sensor on the other side of the same "axle" reads 1 psi low. You now have a condition where the true pressure between left and right is 2 psi different. If each axle has it's own motor, this is not nearly as much of a problem as if they are running through the same differential. Using the same gauge on every tire prevents error stacking.

The fact that it blew out in hot weather is the biggest indicator they were under-inflated although a defective tire cannot be ruled out.

Often problems like this are a combination of factors, some within the driver's control, others beyond their control. That's why I always pro-actively maintain the variables within my control, to reduce the likelihood a tire constructed reasonably well, but with a flaw, might blow out.

Tires vary quite a bit due to variances within the manufacturing process. By running higher pressures, you increase your chances of not having a problem. Pressures on the low side of acceptable greatly increase your chances of having a problem.

Other factors that could increase the chances of excessive heat buildup include sub-optimal wheel alignment and running a ride height that changes the camber of the wheel away from optimal running (tread flat on the pavement). The latter factor could definitely be a cause since changing the ride height changes the camber (and also the toe of the vehicle).

In general, anything that increases rolling resistance will increase heat buildup which greatly increases the chances of having a blowout.

 

[ksurfier]

Definitely not under-pressurized…
Rivian has a Recommended tire pressure, it takes into account the LOAD, CONTACT PATCH, and a number of other parameters (safety, handling, performance, etc.

An acceptable tire pressure range might look something like 38-50 PSI. With 38 being a minimum for load of ~8,000#/4, so each tire carrying ~2,000#.

Track cars will intentionally use lower tire pressure to improve handling characteristics.

while I would aim for 48 psi cold, 45 or 46 psi cold should make almost no difference (slightly larger CP, improved handling)

 

[HaveBlue]

I've had trailer tire issues over the years which is similar to the rivian. When a tire maximum pressure and load rating is close to the weight of the vehicle, the margins for error are small. Just something to keep in mind.

The blow outs I have had were because of under inflation. A 50 psi tire inflated to 45 loses 10% weight rating. When the cumulative rating falls below the weight of the vehicle, they will get hot at speed and blow out. The speed rating also figures in.

The higher the pressure in the tire, the more dramatic when they let loose being 50-100% higher than most tires.

You can run tire tire at any pressure you want so long as the rim does not connect other objects and you do not overheat the tire. The key is the rated contact patch size based on deflection. As you lower the pressure, the contact patch has to get bigger to support the same weight. Ie contact patch area times psi. A big contact patch is good off-road for traction and floatation and the slow speeds won't over heat the tire from all the constant deflection.

Long and short, I got a nail in a tire the day after I picked up my R1S. Pulled it out without losing air. Recently got a screw and had to plug it. These things happen.

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