Let’s math a little, shall we?
5 wheel rotation results in longer tread life when measured by time, but does not increase in tread life when measured by miles.
When using 5 wheel rotation, replacements are more expensive because you replace 5 tires instead of 4.
Over the ownership of the Jeep, does performing 5 wheel rotations save money due to the fact that tires are replaced less often?
Tread life in miles: 40,000
Miles driven in a year: 15,000
Tire replacement cost: $200
Replacement Interval Calculation
4 wheel rotation (“4WR”) – 40,000 miles / 15,000 miles/year = 2.67 year replacement interval (32 months)
5 wheel rotation (“5WR”)– 40,000 miles / (15,000 miles/year x 4/5ths*) = 3.33 year replacement interval (40 months)
Replacement Cost Calculation
4WR – 4 tires x $200 = $800 per replacement
5WR – 5 tires x $200 = $1,000 per replacement
*Let me explain my wear position ratio really quick – In a 5WR there are 5 positions in which a tire may reside; only 4 of those 5 result in the tire incurring mileage wear. If we assume that tires are worn evenly under a rotation method, a 5WR results in each tire only incurring mileage wear for 4/5ths of the total miles driven. So in my example of 15,000 miles/year, a 5WR tire only experiences 12,000 miles of wear because for 3,000 of the total mileage driven (1/5th of 15,000), it was the spare.
Replacement Summary for 360 months (15 years), Detailing Month of Replacement
4WR – 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352 (11 replacements total)
5WR – 40, 80, 120, 160, 200, 240, 280, 320, 360 (9 replacements total)
Tires are replaced at consistent intervals for each method (every 32 and 40 months for 4WR/5WR, respectively) and replacement costs are $200 more expensive for 5WR. However, since a 5WR replaces an extra tire, there are only four 5WR replacements for every five 4WR replacements. The time period necessary to incur four 5WR or five 4WR replacements is 160 months (13.33 years). This is a great interval for assessment, since at month 0 you have all new tires under each method, and month 160 is the first time in which you replace your tires under each method at the same time (thus restarting the 160 month interval again), and consequently the total cost of replacement under each method is the same (there is one less 5WR replacement, but the cost for each of those replacements was 1/5th more). So every 160 months it costs exactly the same to replace tires under either method ($4,000 for 20 tires), but it is true that these costs are not evenly distributed throughout the interval. So the question is: Within the 20 tire/160 month interval, are there more months for which it is less expensive to use a 5WR method?
It’s the same. For 80 of the 160 months the total cost using 4WR is cheaper than 5WR and vice versa for the other 80 months. But again, those months are not evenly distributed. 5WR is favored in the back 80 months, while 4WR is favored in the first 80 months (at a ratio of approximately 70%/30%). In other words, if you were to sell your Jeep at a random month in the first 6.67 years of ownership, you’d be statistically more likely to have saved money by performing a 4WR. If you were to sell it at a random month between 6.67 and 13.33 years, you’d be more likely to have saved money using a 5WR.
So we mathed, and it was pretty cool. But there are more things to take into consideration, and this is where my bias is going to start to show.
- When you do sell your Jeep, what condition do you want your tires/spare in? Depending on where you are in the replacement cycle (either method) you may end up blowing any savings out of the water by having to do an early replacement. Also, do you think a brand new spare equate to +$200 to the selling price?
- At any point in time, would you rather have new tires on your Jeep or old tires? A 5WR lets you keep fresh tires longer, but consequently you end up having worn tires longer as well.
- In the case of a flat, would you rather put on an brand new tire, or a spare that only has 10% life left?
If anyone is curious as to what I do... I do a 4WR, and not really for any of the reasons I stated above. Because I'm shallow and don't want a snaggly-*** tire hanging off the back of my baby. Same reason why I have my wife shop for lingerie at Victoria's Secret and not Walmart; I'm willing to pay more for the things I love to look good.