Will my tires fit?

[deep6]

Hi,
I have a 2007 Mazda 3. I used to have a 2000 Grand Am, and had purchased 4 winter tires for it last year. I was wondering if anyone knew whether the Grand Am's tires will fit on the Mazda 3. I have used the online calculators and it seems like they will only be marginally larger, but when I called a local tire shop, they said the tires "would rub everywhere" and that they'd be too tall.

The Mazda's tire size is: 205/50R-17 and the Grand Am's are: 225/50R-16. I'm looking to put the winters on seperate rims.

Thanks for your help!

[Art]

My son's '05 Mazda 3 had 205/50R17 stock tires which we changed to 215/50R17 (when the original tires wore out) and there was no problem with the fit.

His winter tires were 205/55R16 (dealer recommended winter size) which are the same overall diameter as your 225/50R16 size from the Grand Am.  The Grand Am tires will likely fit ok.  Since you will be getting new wheels, there is nothing to lose with trying them.  If they don't work sell them and get the 205/55R16 size.

The wider tires in the winter may help with ice and packed snow traction but will tend to ride up on slush and not be as good.  If you are a smooth driver the deep snow traction may be improved by riding up on top of it.  If you over throttle the wider tires the traction will be worse by increasing the resistance.

Good luck.   

[Andy@1010tires]

Also note that going to a wider tire wll give you worse traction for winter driving.

[HeliDriver]

Like Art said, I would expect a wider tire to be worse in deep snow and slush, but better on ice and packed snow.

IMO, ice is the nastiest of the winter conditions, so I'm not sure that going narrower for winter is worth the trade-off.

It would be interesting to see some testing done with the same car on the same tire model, but in different widths.

[Andy@1010tires]

Like Art said, I would expect a wider tire to be worse in deep snow and slush, but better on ice and packed snow.

Source?

[Art]

Like Art said, I would expect a wider tire to be worse in deep snow and slush, but better on ice and packed snow.

Source?

Hi Ryan,
I cannot point to a study that was carried out, I know of none.

In my 50 years of driving experience, putting bigger tires on a vehicle that is having trouble with traction solves the problem.  This is always true of a hard surface (dry ashphalt, wet ashphalt, ice and packed snow) but is rarely true for non-hard surfaces (water, slush and often snow) because they tend to cause hydroplaning or high resistance causing traction loss due to spinning.

What my experience and reading has taught me is that traction is much more complicated than just friction (which is not dependent on area) but relates more to the tire area and construction to allow for its deformation with the road surface.  The road surface is not perfectly smooth but "pot marked" and it is the job of the tire to use this un-eveness to "penetrate" the road surface and provide mechanical grip.  Ice and packed snow have pot marks like ashphalt and concrete do, but are more easily damaged by spinning tires.  Increase the surface contact and there will be more traction. Make the tires softer and they will better conform to the irregularities of the surface (particularly ice on a cool day). On dry ashphalt the limiting factor is the tire strength but on ice the limit is the tearing of the ice structure and more tire area reduces both effects.

The width of the rim is also an important consideration.  We are dealing here with stock type wheels.  When going wider on the tire and rim the contact patch is wider and shorter than the stock setup.  But keeping the stock rim width and going 2 sizes up in width will make for a wider and longer footprint.  Mechanical grip is improved on all hard surfaces.

The above is my reasoning for suggesting to deep6 that the larger tires on "stock" 16" rims will improve traction on hard surfaces.  I also looked up on the Mazda 3 forum:  http://www.mazda3forums.com/index.php (you can research as a guest if you don't want to join) wheel tire sizes that fit.  The 225/50R16 will fit fine it appears.  Much larger wheel/tire combinations are popular with those enthusiasts.

Of course the optimal set-up for winter driving for deep6 is the stock winter 205/55R16 winter tires on stock 16 wheels.

Hope this helps.

[HeliDriver]

Like Art said, I would expect a wider tire to be worse in deep snow and slush, but better on ice and packed snow.

Source?

No source, just what seems intuitive to me. I was thinking that more surface area would equal more grip on a smooth surface.

But, supposedly the size of a tire's contact patch doesn't change with changes in width: apparently, if you compare two tires of equal diameter, the narrow one will have a long, narrow contact patch, while the wider one will have a short, wide contact patch, but the surface area of both contact patches will be the same.

I'm still not quite sure that I buy that, but if it is the case, then I could see how the narrower tire would be better in slush and at least equal on ice.

So maybe I'm out to lunch on this.    (It wouldn't be the first time  )

[random006]

Like Art said, I would expect a wider tire to be worse in deep snow and slush, but better on ice and packed snow.

Source?

No source, just what seems intuitive to me. I was thinking that more surface area would equal more grip on a smooth surface.

But, supposedly the size of a tire's contact patch doesn't change with changes in width: apparently, if you compare two tires of equal diameter, the narrow one will have a long, narrow contact patch, while the wider one will have a short, wide contact patch, but the surface area of both contact patches will be the same.

I'm still not quite sure that I buy that, but if it is the case, then I could see how the narrower tire would be better in slush and at least equal on ice.

So maybe I'm out to lunch on this.    (It wouldn't be the first time  )

The wider the tire, the less downward force per unit area is available, potentially resulting in lower traction.  That is why narrower tires are sometimes recommended for winter tires.

The contact patch will be less with a narrower tire of the same diameter.  In fact, I don't think that the length of the patch would differ much for any car or SUV.  There simply isn't that much variation in diameters to make much of a difference.    Of course, you can let all the air out and then the patch would be huge.

[ktm525]

FWIW I find that on the Dakota  with the 265's that the truck pulls and wanders in standing wter/slush. With the 245's on the truck is less affected.

[Nathan@1010tires]

The wider the tire, the less downward force per unit area is available, potentially resulting in lower traction.  That is why narrower tires are sometimes recommended for winter tires.

Bingo.

If you want to get technical, wheel width matters as well.

[HeliDriver]

The wider the tire, the less downward force per unit area is available, potentially resulting in lower traction.  That is why narrower tires are sometimes recommended for winter tires.

Yes, but I can see how that would be a bad thing on ice.

If you read some of the promotional info from Bridgestone/Yokohama, they make a big deal about the microscopic layer of water that forms on the surface of the ice as the tire passes over. That's what all the Shelled Microbubbles and Multicell compounds are for - to evacuate that tiny layer of water that makes ice so slippery.

Since less contact patch equals more downward force per unit area, then the greater pressure will create more water and less traction.

[random006]

The wider the tire, the less downward force per unit area is available, potentially resulting in lower traction.  That is why narrower tires are sometimes recommended for winter tires.

Yes, but I can see how that would be a bad thing on ice.

If you read some of the promotional info from Bridgestone/Yokohama, they make a big deal about the microscopic layer of water that forms on the surface of the ice as the tire passes over. That's what all the Shelled Microbubbles and Multicell compounds are for - to evacuate that tiny layer of water that makes ice so slippery.

Since less contact patch equals more downward force per unit area, then the greater pressure will create more water and less traction.

Not quite.  If you take the narrowing of the tire to ultimate degree, you will end up with a single point of contact, in effect a spike.  The spike would dig into the ice with all that weight above it, not hydroplane.  Imagine a solid rubber bicycle tire full of studs in a single row and you get the idea.

As far as those technologies go, I believe they would still work as they would have less of a contact patch to evacuate, assuming they work in the first place.  It's all a matter of the ratio of those multicell compounds per unit area of rubber.

[HeliDriver]

Well, I'm not sure I agree that if one narrowed a tire to the ultimate degree it would suddenly sprout spikes.    I think what you would end up with is a bicycle tire, plain and simple, or maybe something akin to a giant pizza cutter. I can't imagine a car moving far on either of those.

Here's a press release I found from Yokohama: http://www.cnw.ca/en/releases/archive/October2007/09/c9211.html . It doesn't prove anything, but I found it interesting reading.

[Art]

Well, I'm not sure I agree that if one narrowed a tire to the ultimate degree it would suddenly sprout spikes.    I think what you would end up with is a bicycle tire, plain and simple, or maybe something akin to a giant pizza cutter. I can't imagine a car moving far on either of those.

Here's a press release I found from Yokohama: http://www.cnw.ca/en/releases/archive/October2007/09/c9211.html . It doesn't prove anything, but I found it interesting reading.

That is an interesting article.  It supports your earlier observation that spreading the car's load over a larger tire print will reduce the quantity of water under the tires.  The tire manufacturers seem to use that same reasoning when optimizing a winter tire for ice by having larger rubber surfaces and smaller channels while snow/slush optimized winter tires have smaller rubber surfaces and larger channels.

It works for me too.