Toyota and other vehicle brands use wheel lug nuts that become "swollen" over time. This happens because a cosmetic cap (with no mechanical purpose) made from a different metal is bonded over the metal of the lug nut. The cosmetic cap deforms or swells, because of its different properties compared to the lug nut itself. On 12 August 2021 I was unable to change a flat tire because the lug nut wrench that came with the vehicle no longer would fit over the lug nuts in order to loosen them. The lug nut wrench would not fit any of the 20 lug nuts on the vehicle. There is not one single mention in the 636-page owner's manual about swollen lug nuts, only an advisory to use genuine Toyota wheel nuts and wrenches, which easily become incompatible. The genuine Toyota wrench no longer fit, I had no other means of loosening the lug nuts, and became stranded. I was fortunate that a friendly motorist with a set of different sockets and a breaker bar came along and was able to assist me. Such fortune is not always the case. Being stranded puts the personal safety of the motorist in jeopardy, as can be confirmed in numerous reported incidences. On 13 August 2021 I went to the dealer to repair / replace the flat tire. The dealer acknowledged that the swollen lug nuts were a known mechanical defect with many Toyota vehicles, but refused to install lug nuts on my vehicle without this defect. The only recourse offered was for me to buy new lug nuts of the same style, which would not have improved the situation. Because of the personal safety issues involved, intentionally selling vehicles with know mechanical defects to unsuspecting buyers should come with serious consequences for a manufacturer. Refusing to repair such defects when pointed out to the dealers should also carry consequences.

- Story City, IA, USA

Lug nuts are 2-piece: Steel nuts with chromed covers crimped on. The nuts rust inside the chrome covers and swell so that the lug wrench that comes with the vehicle (nor sockets or typical 4-way lug wrenches) will not fit the nut. One can be stranded on the side of the road unable to remove a flat tire. Besides the wheel locks, all 16 of the remaining nuts were affected. I have ordered replacement nuts, on advice from my local tire shop, that are chrome plated and not 2-piece. I informed Toyota customer service of the problem and they acknowledged receipt butoffered no solution or compensation. The problem occurred when I needed to remove a tire, but thankfully it was still driveable. My local tire shop was able to hammer-on a socket to remove the swollen nuts, and I will have to return to them to have them install the replacement nuts. I am retaining the original nuts in case they are needed by NHTSA or Toyota for examination. There are many reports of this issue online, as well as mentions in product questions about replacement nuts on amazon.com (eg, are these nuts one-piece or not, and reports of this exact problem with many vehicles). Interestingly, it turns out that tool manufacturer snap-on makes an 18.5mm and 19.5mm oversized sockets to remove these swollen nuts. The problem is common enough for specialized tools. Please act on this to prevent some poor individual from being stranded!

- Chester, NJ, USA

I was driving on I-35 and has to stop at the shoulder for about 30 seconds to fix something. The shoulder is smooth and newly paved. Then I went on driving again, minutes late, the tire low air indicator was on and a few more minutes later, the left front tire was totally flat. The tire has only 7500 miles on it and was told by Toyota dealer that I need to purchase a new one. And there is no warranty on it since it is from a new car and I did not purchase their extended coverage. I think it is quality of the tire used and I saw tons of same complaints from other Toyota Highlander owners.

- Lenexa, KS, USA