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Razorback

2 Different Sizes

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I remember when most cars back in the 60's & 70's had the same size tires on all four wheels except for those cars that were fixed up or some of the muscle cars.The last car that I purchased recently has two diffrent size tires on the front and rear. The smarts will be having two different size wheels on the front and rear so I was wondering if a person could trade with someone else wheels (rims) for the same size so the front and back wheels would could be the same size so it would be possible to rotate your cars tires for more tread longevity rather than having to change out two tires at a time.What do you think of the possibility of doing this and just what are the pros and cons of having two different size tires on a smart car?

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The reason the sizes are different is that smart needed to dial some excessive understeer into the car to make it handle safely...after the suspension had already been designed.....so the easiest way to do that was to put narrower tires on the front.Some do have the same size of tire all around, but it's impossible - I daresay ;) - to find a set of wheels that would carry the same size of tire AND be interchangable from the front to the rear axle. The offsets are quite different from front to rear. Even if you could find it, the cost would negate the benefit in terms of evening tire wear. And what's wrong with buying two at a time? It's cheaper that way!In my experience the OEM Continental tires seem to be good for about 50,000 miles in fairly gentle driving, so you may not have to deal with tire replacements for a few years anyway.

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I dare say after 118,000 kms of driving a smart, the tires tend to wear evenly with the exception of the rear right tire, which is the drive wheel - it wears slightly quicker, but still evenly. And I never have had an alignment despite thinking that would be required yearly.

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Was it winter time when you bought your car? Did you get it from O'Regans or whatever the Halifax dealership is called?

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I never knew that. Well I guess today was not a waste of time because it is already 10:30 and I learned something new.

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Having had the Bridgestones and steel rims I can honestly say that there is no comparison to alloy wheels with Conti's. It could however also be the fact that the new wheels are larger than the stock ones.

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It's the bridgestones. My fronts started chirping every time I stopped after 3000km. Hands would cramp up trying to keep it straight on the highway with a crosswind. The term I liked was "controlled skating" :smirk:

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I dare say after 118,000 kms of driving a smart, the tires tend to wear evenly with the exception of the rear right tire, which is the drive wheel - it wears slightly quicker, but still evenly. And I never have had an alignment despite thinking that would be required yearly.

Really? I'm sure there are two axle's under there. You mean that the Right rear gets more power from the engine than the left? At least you can rotate tires left to right in the back and the front, that's what I do each season when I switch between summers and winters (on steelies).

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The reason for the differences in wear rate are explained by differential function...so I am led to believe...

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I can sort of understand this, it's why you experience torque steer in front wheel drive vehicles. Supposedly the wheel with the shorter axle experiences more torque than the wheel with the longer axle.I'm not sure that this applies to the smart though.

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The axles are very much unequal length in a smart too!Watch a car without a limited slip differential do a burnout. The right tire will always spin first in a RWD vehicle!

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For sure, my rear right was worn substantially more than the left rear upon return from my trip acorss Canada in 2005. And the fronts still had 50% life when the rears were at the wear bars, BTW...FWIW - I saw a set of Vredesteins at fasteddy's today, and they looked SUPER NICE. Quadtrac 2's in 175/195.

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The reason for the differences in wear rate are explained by differential function...so I am led to believe...

Power is sent to the differential and via the crown & pinion gears and the spider gears it is directed firstly to the R/R and then to the L/R. Slipage in the R/R tire's traction accounts for the faster wear. The same thing occurs on tandem drive highway trucks where the power is sent to the rear axle first via the power divider and on to R/R first and the L/R second. The R/R dual tires will exhibit similar accelerated wear if not rotated. "tis almost the season to experiment if one is so inclined. Park on a sheet of ice and gradually apply power. Note which wheel spins first. (the weight on each wheel needs to be the same for accurate demonstration)The length of the axle really has no bearing on whether it is the 'power/drive axle' or not. It depends on crankshaft rotation and the side the crown gear is on the differential in the go forward configuration. NTV's mention of torque steer is a good example of the effect.

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Do front wheel drive vehicles, and the smart, (or any vehicle with a transverse mounted engine) have pinion gears? I didn't think they would since there is no need to transfer power 90 degrees. (well, my pre 1993 Saab 900's are front wheel drive and have longitudinally mounted engines, and there is a pinion and crown gear differential in them, it's a pretty cool setup.)

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