Posted by MattI just had new tires put on my car and thought I would share the details of my shopping experience, which was much more complicated than I initially expected. Before I get into that, however, I wanted to point out that maintaining your tires properly prolongs their lifespan, which is the easiest way to save money on them. I have recurring reminders on my google calendar to check my tire pressure monthly (see the box on "Tire Inflation" here) and get the tires rotated and brakes inspected (annually, which corresponds to every 7500 miles) at my favorite local shop.
The shop mechanic who last rotated my tires was the person who actually recommended new tires, but I didn't take his word for it. I checked the wear bars and also used the coin tests. My tires hadn't worn perfectly evenly, but they were close and one of them definitely needed replacing.
So, I went back to the tire shop and they gave me a list showing tires from their inventory that were compatible with my car.
I ask whether any of the tires on the list were designated as "low rolling resistance" tires, as I had heard that this could save money by improving gas mileage, but the clerk didn't seem to know anything about this. I also asked about the age of their inventory, but was reassured that the shop sold enough tires that they didn't have a problem with tires aging on the shelf.
The list of available tires was short, but unfortunately, I wasn't quite sure how to comparison shop. I found a very helpful article on HowStuffWorks that helped me interpret the sidewall codes used by the tire industry to categorize their tires.
Here's an example from my shopping list: P195/60R15 87T M+S
P - Type of tire (passenger)
195 - width of the tire across the tread in millimeters
60 - Aspect ratio of the sidewall compared to the width
R - Radial construction
15 - Diameter of the rim in inches
87 - Tire's load rating
T - Tire's speed rating
M+S - Mud+Snow, meaning the tire is suitable for all-season driving
All of the codes my shopping list were similar (because they primarily describe sizing) but I noticed one important variable: the speed rating. The "T" in the code for these tires means that they are rated as safe to drive up to 118mph. The other tires on my shopping list were rated "H", meaning they were safe up to 130mph. This didn't really concern me, as I don't plan on driving anywhere near 118mph, much less 130, but the shop told me that the T-rated tires would last for 70k miles, whereas the H-rated tire sets would last between 40k and 50k miles. The explanation from About.com:
The faster a tire can go, the softer the rubber compound they use to make it (softer rubber grips dry pavement better), so the tire will wear out faster than a "slower" rated tire.The T-rated tires were priced a little higher, but only until I made the comparison fair by computing how many dollars it would cost me per mile of service life:
| Warranty (Miles) | Price | Miles per dollar |
|---|---|---|
| 40,000 | 247.96 | 161.32 |
| 45,000 | 307.64 | 146.27 |
| 50,000 | 337.80 | 148.02 |
| 70,000 | 356.80 | 196.19 |
Based on this, the high mileage tire looks like a great deal. This is just what the shop clerk told me, but I'm always skeptical of the sales pitch, of course. I also worried that I would sell the car before going another 70,000 miles (which equates to about ten years of driving for me) but decided to gamble. Who knows how long I'll have to wait for an affordable electric car?
Next, I decided I should check online prices, but I didn't find any cheaper deals, especially considering that I would have to pay for shipping (around $50) and then pay to have the tires mounted/balanced/installed.
The tire shop also wanted to sell me siping for an additional $50, but I declined based mostly on a Consumer Reports article indicating that siping was most helpful in snow and ice conditions, which I don't encounter often.
The only real bad news in this story is that the quotes that the clerk initially offered me had expired by the time I had finished doing all of this analysis! Luckily, it was very simple to apply the lessons learned to pick from their current inventory list and I'm satisfied that I still found a good deal. Barring any advances in tire technology in the next 10 years (what are the odds?), I should be well prepared for the next set, too.
