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Tire Size?

What are the advantages and/or disadvantages of installing 205/50R16 tires when the manufacturer recommends 205/45R16? More or less should this option even be considered? *For the record I drive a 2010 Kia Rio5.

The 50 series tire will have a slightly taller sidewall and therefore will have a slightly larger circumference. This means it will alter your speedo readings a bit on the lower side, you’ll be traveling 1-3 mph faster with the same indicated speed as a 45 series tire.

The 50 series should fit on the same rim, but a tire shop would have to confirm that. Unless the wheel well in the Rio5 is very tight it should not rub on the frame or bodywork. No advantage or disadvantage in performance. Is this a situation where the 50 series tire is a lot cheaper than the 45? Why are you looking at a different size from OEM specs?

There is the matter of clearance when going to a larger tire - and unless someone actually measures the fenderwell, they can’t say for certain a size will fit or not. If a tire rubs, it could be very bad!

But you should be aware that changing to a different tires has a much more dramatic affect than a change in tire size.

My advice would be to stick with the stock size and carefully chose a tire that fits your needs.

If according to the manufacturer, the larger size is not listed as an option, you have little choice but to heed Capri and Uncle Turbo’s advice. The only way to go to a higher profile tire with the same outside circumference is to go to a smaller rim that fits. If that’s not possible or worthwhile, stay with what you have.

There are too many traction aids on cars that use rotation calibration from the abs system to mess with changing tire sizes from that recomended. The only exception would be after inquiring from the manufacturer and getting their blessing to use different tire sizes.

Those two tires are VERY close to being identical…I don’t think you will be able to tell the difference…

Today’s proliferation of tire sizes is insane. Only the largest tire retailers can BEGIN to stock all the various sizes and types of tires available…

I don’t know why anyone would disagree with Caddyman. The tire size is very close to the original and to many drivers not have a discernible difference to them. But, the the rest of the mechanics that have to deal with the traction and stability control may be a problem that only the manufacturer can tell. I have had different opinions on different vehicles.

Trucks (like my 4Runner) for example, even with traction aids can successfully up size a little. Many full time awd cars may have problems for a variety of reasons including fitment. You don’t want the system to be confused anymore then necessary in an emergency situation, but some vehicles may be programed to handle it.

What you don’t ever want to do is just change 4 tires without including the spare in an awd/4 wd vehicle. That one time you need it may render your awd vehicle permanently impaired if you do. The Toyota people say up sizing my 4runner one size is ok but the spare wheel well has trouble fitting an up size spare and using a different from standard tow hitch, the clearance is so small. This may necessitate lowering the pressure and force fitting it in place. Stuff like this and other inconveniences just doesn’t make it worth it.

Consider too that some winter tires with much deeper treads have a larger circumference when new then the summer spare you carry around, and aggressive ones are not far from that one extra size larger. Confusing with tires and I agree with Caddyman…somewhat.

All good advice. If you look at different brands of tire with the same size. The actual measurements can and do differ. So look at the measurements of both to see how much they do differ.

Ask to see a 205/50R/16 and a 205/45R/16 placed next to each other on the showroom floor…

They will be almost identical, with the 205/50/16 standing an inch higher, maybe…

More than likely, the tire store will not have both sizes in stock and won’t be able to make the comparison and the 45 series tire will cost considerably more than the 50 series…

Manufacturers often provide 3 or 4 different size tires for the same model car as options for buyers so there is seldom a single stock tire size. My 2007 Prius was available with 15 or 16 inch rims and my 2011 Chevy truck was available with 17, 18, or 20 inch rims.

You can find online tire size calculators where you can input the tire specs and find the exact tire height or diameter for you current tires and for new ones you are considering. Width is equally important for the front tires to keep them from hitting parts of the car when making a turn.

Rule of thumb is not to use tires that are more than 3% different in diameter. The difference between a 205/45R16 and a 205/50R16 is …[drumroll]… 3.4%.

So, yes, it is significantly different.

I agree. 3% is not significant when mixing powdered milk. It is significant to a car where tolerances are measured to .001 Unit measure.

I would be willing to bet the speedometer / odometer is running 3-5% fast with the STOCK tire size. So by installing a SLIGHTLY larger tire, you can “calibrate” your speedometer/odometer to read spot on!

Dagosa is confusing tires with main bearings!

So you don’t think the the electronics used in todays cars to monitor speed have tolerances of equal to that of wheel bearings ? Or, the hardware used in the abs system to operate your traction/stability control…etc. I agree that the seat cushions and tires can have measurements that are not that critical…but only if the software is designed to accept in the case of a car’s computer when controlling the traction devises. IMO, the greater the accepted tolerance in this case, the less effective the device.

From a software/hardware standpoint if all 4 tires are changed how will the electronics know? There is not a wind speed sensor? Is it feedback from the navigation system that will give the body control module the information? It has been 3 years since I looked at engine controllers but I am not aware of a closed loop between the rotational speed of the wheel had the actual vehicle speed.

1 inch taller overall/ 0.5inch taller from wheel hub to outer tire I would not expect any difference from the vehicle except a little offset in speedometer.

Guess I didn’t make myself clear. I was responding to Caddy man about the hardware only. Whether it used the cable of old or the sensors of new cars, the car speedometer will read slightly lower then actual speeds. I think we are talking about two different things here.

Technicians have told me, on some cars it is very important not to change tire sizes (circumference) from original while on some vehicles, some small change is acceptable. I still maintain it depends upon the car.

Please read this discussion in general on modifications (including tires) and how it affects these traction aids. The brunt of he discussion is trucks and perhaps there is a lot of CYA in recommending you not change tire circumference on cars with electronic aids. I’m not ready to have the techs I have talk to take the stand on the part of my insurance company interested in non payment for an accident…are you ?

I read that discussion and so far it applies to 2012 vehicles and newer. I agree with most of what was said in that article but come on. 1 inch overall diameter should make no difference anywhere on the same rim.

And if it were 2 inches we wouldn’t be having this conversation. In the future you may be proven right and one inch should not make any difference. But as addressed in the article, not enough is known and my cars won’t be a statistic that finally proves or disproves what you say. I check with the manufacturer and the technicians regardless and continue to recomend anyone else do as well.

Btw, any restriction on discussions to 2012 models has more to do with the mandate for that year that all cars and light duty trucks come equi with the electronic aids. Many cars and trucks for years have been made with them…they become part of the conversation if the car has the system(s).

I find this whole discussion very interesting. Lots of opinions as to how big is too big, but very little of it is based on actual measurements. Is there anyone who publishes a list of what fits based on actual measurements of the vehicle involved?

Why, yes, there is: Discount Tire

On their website, if you put in the vehicle information, they will tell you what the original tire size was - and give you optional fitments based on their measurements of the vehicle

And guess what: a 2010 Kia Rio5 doesn’t show a 205/50R16 as an optional fitment… They show a 195/50R16, and a 215/45R16.

Conclusion? The OP should NOT do what he is contemplating. Discount Tire says it won’t fit.

Here in Al and I am sure elsewhere, there are many drivers of newer vehicles with very large rims/tires on them. I wonder how the electronic stability handles that case? Many of these are newer Chrysler/Dodge product also that I know have stability programs.

My Monte Carlo SS had no complaints from riding with my 2008 Dodge Magnum wheels on it. They were 1 inch taller.

Discount Tire does not say it won’t fit. They just say it was not a size available from the factory…

Today, one just has to look around to see unlimited numbers of cars and trucks fitted with tires/wheels that are FAR removed from what the “factory recommends”…Do these radical tire/wheel combinations pose a threat to Public Safety of National Security?? Apparently not…