While I'm not an expert, a tariff is just another externality -- albeit one that hits imports harder than domestic goods. It depends on the size of the costs, how much it impacts the bottom line, and whether the company can take the hit.
Let's say that an imported truck costs $30,000 and is hit with a steel tariff that increases the cost by 2%. The company might absorb some of the costs, and pass some of it on, or find a way to remove $600 worth of options from next year's model. The company has more latitude because it's a relatively small change. If the company is doing well overall, it can afford the price change. If the company is already having a hard time, it's screwed -- because it might not be able to handle either the lost profits if they absorb the costs, or the lost sales when prices go up.
The following year, the government puts a 25% tariff on all imported trucks. I'm pretty sure no company can absorb that hit, so the vast majority of the cost will be passed on to the consumer.
We should note that tariffs don't make domestic goods cheaper. In some cases, it can make domestic offerings more expensive! For example, China was dumping cheap steel on international markets for years, and American steel companies complained about it. Obama slapped tariffs that were 250% to 522% on that steel. What happened? The Chinese steel got more expensive in the US -- and US steel companies raised their prices, because they could do so and still undercut the Chinese offerings. Chinese companies did an end-run around the tariffs by routing them through Vietnam for years (until they got caught, and nailed Vietnamese steel with a 500% tariff). Cheap Chinese steel was still available outside the US, so US steel exports went nowhere. Since steel was more expensive in the US, some of the costs were passed on to consumers; since the steel industry is heavily automated, few American steel jobs were preserved.
