I have purchased a 2010 Toyota Venza with 20-inch rubber. Last month, the Toyota dealer had a bunch of us in for a captive sales pitch for service, aftermarket stuff and winter rubber. I asked if they had steel rims at 20 inches for the winter tires and they said no. They had 17-inch steel rims and said we would have to use them. What are we doing here? Is this not over the safety boundary that you mentioned in an earlier column? – Spd in St. Catharines, Ont.
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This is the most frequently asked question in my inbox and one that tire stores are inundated with.
Two things are at play here:
- Toyota sells a lot of cars/vehicles so the demand for winter or replacement tires is high.
- The Venza, Highlander and Camry are all built on the same platform or underpinnings. In other words, they are all alike under the skin, with similar engines, transmissions, brakes – and tires.
The latter is where the answer to your question lies – and the reason the dealer has 17-inch steel wheels that will fit.
Assuming the wheels fit over the brakes and have the proper bolt pattern and offset – i.e. the centerline lies in the same exact spec, 16-, 17-, 18-, 19- and 20-inch wheels from or designed for the Camry, Highlander or Venza will fit and work.
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The 16-inch steel wheel that is standard equipment on the least-expensive Camry has the same offset and bolt pattern as the 20-inch wheel on your Venza.
But the next step is where safety issue comes into play – what size tire you install on those wheels or rims. We have the offset, bolt pattern and brake clearance covered, but wrapping the wheel with the wrong-size tire can create huge problems.
The issue is the overall diameter of the wheel/tire combination. This in turn dictates how many times or revolutions the tire and wheel will turn in any given distance, expressed in revs per mile or kilometre.
A great many dynamic functions are keyed to the revs per mile. These range from very important things like ABS, electronic stability control and handling to non-safety issues like fuel mileage, speedometer accuracy and even automatic shift transmission shifts. During the development of the vehicle, engineers specify the revs/km of the tire with all these factored in – so changing that circumference can be dangerous.
It is generally accepted that if you keep within 1 to 3 per cent you are okay. The earlier example you were referring to was outside that range.
To put numbers to the extremes of this Toyota size issue:
The 245/50R 20 tire that came on your Venza has an overall diameter of 752.85 mm, sidewall height of 122.4 mm, circumference is 2,365 mm and turns 423 times every kilometre.
A 245/65R 17 tire on the steel wheel recommended by your dealer has a diameter of 431.8 mm, circumference of 2,356 mm and turns 424 revs/km.
That will result in a slight, but acceptable, speedometer error. When it reads 100 you will actually be travelling at 99.8. That is not an issue since there is not a speedometer in the industry accurate to within that 0.2 per cent error.
The short answer is yes, you are okay with the 17-inch wheel and a proper-size tire.
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