
If the tread wear on the car tire is still relatively shallow, you can replace just one tire. In this case, the wear on the tires on the same axle is actually similar, but it is essential to ensure that the tread pattern, structure, brand, and specifications of the tires on the same axle are identical. If the tread wear is severe, replacing just one tire can significantly impact driving safety, potentially causing the vehicle to pull to one side or even lose control. This is because a severely worn tire has less friction and grip compared to a new tire. If only one tire is replaced, the difference in grip strength between the new and old tires can lead to pulling or loss of control. Additionally, the vehicle may experience uneven height, leading to bumpiness or pulling issues at higher speeds. Therefore, in such cases, it is best to replace a pair of tires. The placement of new tires on a car is also crucial. Generally, new tires should be installed on the drive wheels. For front-wheel-drive vehicles, new tires should be placed on the front wheels, while for rear-wheel-drive vehicles, they should be placed on the rear wheels. In front-wheel-drive vehicles, the front wheels serve as both steering and drive wheels, requiring strong grip during emergency braking, hence the need for new tires on the front wheels. For rear-wheel-drive vehicles, the rear wheels are prone to slipping as the power is concentrated on them. If the wear is excessive, the rear wheels' grip weakens, so new tires should be placed on the rear wheels to prevent rollovers.

I've been driving for over 20 years and have seen many car owners trying to save money by replacing just one rear tire, but this is really not recommended. Tire wear must be even. If you only replace one tire, the new one will have deeper treads while the old one is worn flat, leading to differences in grip. This can cause the car to veer or skid when driving at high speeds or in rainy conditions, increasing the risk of accidents. Every time I do maintenance, I remind everyone to check the wear and tire pressure of the rear tires. If one is damaged, it's best to replace both tires on the same axle to ensure balance. New cars can handle it better, but older cars need extra caution as the suspension system is under more stress. Remember, safe driving is more important than anything else. Spending a bit more to replace a pair of tires is more reassuring and, in the long run, protects other parts of the vehicle.

From a cost-saving perspective, replacing just one rear tire can sometimes be feasible, especially if the other three tires are still relatively new with minimal wear difference. I've done this myself for city commuting without major issues. However, you must ensure the new tire matches the size and tread pattern of the existing ones - otherwise it may feel odd to drive with increased wind noise. In the long run, uneven tire wear can accelerate the deterioration of other wheels, potentially forcing you to replace all tires sooner at greater expense. I recommend measuring the tread depth first - if the difference exceeds 2mm, don't cut corners. Regularly checking tire pressure and visual condition yourself is also crucial. Addressing issues promptly achieves both savings and safety.

Just replace one rear tire? It's not recommended. Experience tells me that tires should be replaced in pairs. The wear difference between old and new tires can make the car unstable, especially since the rear wheels handle propulsion—imbalance makes steering difficult and increases risks in rainy conditions. Check if replacement is absolutely necessary, or consider changing a pair for better safety. Simple and practical, don't skimp on that expense.

As a car enthusiast, I always pay attention to these details. Technically, it's possible to replace just one rear tire, but there are conditions: the tread depth difference between the old tires must be within the allowable range, and they must be of the same model. I've measured it – excessive differences can cause excessive suspension wear and uneven grip. Use a tread depth gauge and tire pressure gauge to check. Safety comes first, so take immediate action if there are any issues.