The stock tire size on the MPV is 215/60-16, which basically means the tire is 215mm wide, the tire is 60% as tall as it is wide and is designed for a 16" wheel. Last year after I selected the tire I called around to different tire shops to see who had the tire I wanted in that size for the best price.

If you want to know more about tire sizes check out this link. For a handy tire size calculator see this page

You have to be careful when you are dealing with tire shops, frequently they will quote you a reasonable sounding price for the tire then they tack on high fees for mounting & balancing and lots of extras like new valve stems (usually not necessary) and whatever other things they can stick on there to charge you more. The bigger chains are more likely to try this than the smaller shops.

Another thing about tire shops, they HATE it when you know exactly what kind of tire you want before you call, usually you call them and tell them you want a price quote for some tires they ask you what size you are looking for, because they want to choose what tire you get. Usually it will be an off-brand tire about the same quality level as the factory tires ad a moderately lower price than the factory tires. Of course the profit for the shop for these tires is outrageous since they cost the shop FAR less. The shops assume (usually correctly) that the average consumer doesn't know anything about tires and that if they tell the customer that the factory Goodyear costs $120/tire and they have these tires which are justs as good (true but that's not saying much) for only $100/tire the customer will feel like they are getting a great deal. What the truth is that the tire store paid only $60 for that tire they sell to you for $100,t hey they usually charge you another $20/tire for mounting, balancing & other stuff. When I was young & stupid I myself fell into this trap, luckily now I am better informed.

After I called around, told them the specific tire model as well as the size I wanted I found, as I suspected, that the best "out the door" price was from a small local shop I have done business before. Their price was typically a little bit more than the Tire Racks but came out cheaper in total because I didn't have to pay for shipping. Since the tires I wanted weren't the expensive "top brand" tires nor the tire shops favorite brand they had to get them from the warehouse, this is normal and usually takes a day or two at most. After I ordered the tires I got a call a couple days later that they had arrived.

When I drove the van to the shop I found to my dismay that they had ordered completely the wrong size (15"). They say they would order the right ones and off I go with one wasted trip. A couple days later I get another call, the new tires are here. Back to the shop I go and find that they again got it wrong, this time they ordered 225/60-16 instead of the stock size of 215/50-16, my quick calculation in my head tells me the ones they ordered are a hair (10mm) wider and a teency bit taller. I'm OK with this so I have them go ahead and mount the tires, they work great and all is well.

This brings me to a side note about tire sizes and the effect on your speedometer & odometer. Many people aren't aware that their cars speedometer is almost never accurate from the factory, furthermore it's almost always fast by 1-2%.

Now I know it's not reasonable to expect that every car coming off the factory to have a 100% accurate speedometer, there are too many variables, from tire size variances to alignment differences to who knows what. A 3% variance in accuracy is generally considered acceptable.

Now logically if the speedometer inaccuracy was really caused by random variances you would expect to see random errors, with some vehicles speedometers reading a little slow, some a little fast, and a lucky few right on the money. The reality is much different, which is that speedometers almost always run fast.

Usually car companies will deny this, when they do acknowledge it they say they error on the side of reading too fast because they would NEVER want you to be actually going faster than you thought you were.

I have a different theory, which is backed by absolutely no proof, my theory is that the car companies do make the speedometer fast on purpose, and that they do this so that your warranty will run out faster.

In my Mazda3 my speedometer reads about 2MPH fast at 60MPH (calibrated against two different GPS units), which means when my speedometer reads 60 I'm really going 58. This is right about at the 3% limit, which means even if I complained to the dealer they won't fix it. Now you may be thinking that 2MPH doesn't seem like much, but the net result is that when my warranty expires it will be 1800 miles sooner than if my speedometer was 100% accurate.

For the record, the tires for the MPV were about 1% larger than the stock size, which means that it would make a correctly calibrated speedometer read 1% slow. I have estimated the error in the MPV at about 2% so with the larger tires the speedometer reads closer to accurate but still about 1% fast.

In any case, fast forward to a few months ago and I need to replace the other two tires. I call around again, this time asking for the larger size, the same shop again has the cheapest out the door price so I order.

A week goes by and I hear nothing, we go on a camping trip and have to travel on a rough road, this road actually pushes one of the old tires over the edge and it develops a large bulge, which creates a lot of vibration and is none too safe. Since the shop is closed on Sunday (the day we got back from camping) and I didn't want Tove to go to work on Monday with the bulged tire I go to the local Mexicali tire and get a used tire for $20 to replace the bulged one.

Since the immediate need is passed and I'm busy I don't think about it for a few more weeks, when I call the tire shop back I find they had completely forgotten about the order, they promise to re-order right away.

A month passes and they still haven't called so I call them back again, this time they say the tire was on backorder and it would be at least another month before it came in (WTF).

So now I call around again, I find that all the other shops have the same backorder story, and most of them want to charge $20/tire more than the original shop.

This brought me to the Tire Rack, they have the tire for $60/ea, shipping will be about $20 so I'm paying about $70/tire, I'll have to pay another $8/tire to have Mexicali mount & balance them so I'll be looking at about $80/tire when all is said and done. This is about $10/tire more than if I could get it from the local shop but they seem to be having stupidity issues so I guess that isn't meant to be.

The Tire Rack caught that the tire size was different from OEM, they even called me today because of that, but once I told them I knew about it and that it was indeed what I wanted they were like "OK, cool". It's supposed to be 2 day shipping so if the order goes out today I should get it on Friday.

Another side note on the issue of OEM (factory) tires. On all but the highest performance cars you get stuck with "All Season" tires, with an All Season tire the tread is designed to give up a large amount of wet traction and a HUGE amount of dry traction to provide a very small amount of snow & ice traction.

Since it hasn't snowed here in decades I always go with summer tires, which provide far superior wet & dry traction. If I lived where it snowed I'd still have summer tires and a set of winter tires that I would use just for the winter months.

In fact "All Season" tires are probably one of the most extreme examples of when something tries to be a jack of all trades and a master at none, they suck when it's sunny, they suck when it's raining and they suck when it's snowy.

Also with factory tires you usually get the "top brand" tires such as Goodyear, Michelin or Firestone. Now you would think that the car companies wouldn't want to pay a premium for these brands of tires, and would go with cheaper lesser known brands instead. The kicker here is that the manufacturers don't pay the premium.

Because of economies of scale it actually costs Goodyear less to make a tire than a lesser known brand, but they sell for much much more, when Goodyear sells to a company like Mazda they sell for much closer to cost. So the craptacular Goodyear Eagle RS-As that came on my car may have a list price of about $120/tire but Mazda probably pays only about $40/tire.

Why do the tire companies cut such sweet deals with the car companies? Well the first obvious answer is volume, Mazda buys more tires a year than a whole chain of tire shops, the second is less obvious and more nefarious.

People have a tendancy to want to get exactly the same tires as the ones that came on their car, they also generally believe that the more expensive something is the better it is. So Goodyear (using Goodyear as an example since my Mazda3 came with craptacular Goodyear Eagle RS-A tires) sells the tires to Mazda for not much over cost then sits back and rapes the consumer on the replacements.

Obviously not everyone buys the overpriced underperforming "top brand" tires as replacement, there are a lot of people who buy less overpriced but still underperforming lesser known brands and there are a few people like me who shop for tires as carefully as they shop for the car they go on.

Still, you have more than enough people buying tires at more than 100% over cost (that's wholesale, it's closer to 200% once you pay for it in a tire shop) to make it very worthwhile for the "top brands" to give a big discount to the car companies, and since the "top brands" have lower cost they can almost always undercut the price of the lesser known brands.