Snow Tire Question: Downsizing

Shouldn't cause any problems. Your speedo will be a lil too fast and you'll lose ground clearance but that's about it

Unless for some reason the wheels don't fit over the brakes or they're some weird offset where they start rubbing components you'll be fine

whoever decided tires sizes should be designated as they are was on crack

No.Quarterwhoever decided tires sizes should be designated as they are was on crack

It's a super easy to learn and understand system. I see no issues with it other than it uses both metric and imperial measurements.

As for downsized tires: It'll change your mileage a bit, your apparent torque, your speedometer will be a bit off, and lower clearance. Otherwise not a big deal. Consider that going from new tires to bald tires the wear is somewhere around 3/8", so a total diameter change of 3/4". Narrow vs wider tires would make a larger difference for winter driving.

coronaIt's a super easy to learn and understand system. I see no issues with it other than it uses both metric and imperial measurements.

It's got metric, imperial, ratios, and people refer to off road tires in inch diameter as well. Just as fucky as the bike industry and only understandable to those who are well versed in the lingo. Some of the conversations I have with staff members at bike shops about standards and component specs seem completely nonsensical

skiP.E.I.Has anyone downsized their snow tires from their summers/all seasons? I have a mint set of 185 65 14 winter tires on rims. Currently the car has 185 65 15s installed. Rims have the same bolt pattern.
Will it cause problems if I use the 1" smaller tires?
**Obviously NS isn't a great place to ask for mechanical advice, but I thought some of you might also drive in snow and may have tried this.**

Used to work at Discount Tire so I actually know what I'm talking about.

You said bolt pattern is the same, so you're good there.

Compare backspacing on the new wheels to your current wheel. Backspacing is the distance between the back of the rim and the mounting flange on the wheel. You want that to be the same (or pretty close) on both wheels.

Make sure the new 14" wheel fits over your brakes. Test both the front and rears, as they're likely different sized brakes. Mount the new wheel and spin it while the car is jacked up in the air. If nothing is grinding or hitting anything, you're good to go.

BrandoComandoUsed to work at Discount Tire so I actually know what I'm talking about.

You said bolt pattern is the same, so you're good there.

Compare backspacing on the new wheels to your current wheel. Backspacing is the distance between the back of the rim and the mounting flange on the wheel. You want that to be the same (or pretty close) on both wheels.

Make sure the new 14" wheel fits over your brakes. Test both the front and rears, as they're likely different sized brakes. Mount the new wheel and spin it while the car is jacked up in the air. If nothing is grinding or hitting anything, you're good to go.

This guy knows what he is talking about. Tire size doesn’t matter, what matter is if the rims will fit, and there is a lot more to rims fitting than the bolt pattern.

if you have the tires though, easy way to see if the rims will fit is just try and install them.

No.QuarterIt's got metric, imperial, ratios, and people refer to off road tires in inch diameter as well. Just as fucky as the bike industry and only understandable to those who are well versed in the lingo. Some of the conversations I have with staff members at bike shops about standards and component specs seem completely nonsensical

What do you suggest is a better system?

From 3 numbers the current system gives you: tire width, tire profile, rim diameter, and total diameter.

The only big improvement I can see would be to standardize to just metric (all measurements in mm). You could swap around some of the numbers, but it would still require a minimum of 3 numbers to get all the information.

Something like:
195-630-380?
Width, diameter, wheel diameter?

coronaWhat do you suggest is a better system?

From 3 numbers the current system gives you: tire width, tire profile, rim diameter, and total diameter.

The only big improvement I can see would be to standardize to just metric (all measurements in mm). You could swap around some of the numbers, but it would still require a minimum of 3 numbers to get all the information.

Something like:
195-630-380?
Width, diameter, wheel diameter?

I'm not really suggesting anything better, just commenting on how funny it seems and how it can seem daunting for people who don't know much about cars. I guess committing to imperial sizing and overall diameter rather than aspect ratio is what I would think is best, as much as I dislike imperial units, rim sizing has adopted imperial for the most part, except for bolt pattern which is irrelevant to tire sizing.

coronaWhat do you suggest is a better system?

From 3 numbers the current system gives you: tire width, tire profile, rim diameter, and total diameter.

The only big improvement I can see would be to standardize to just metric (all measurements in mm). You could swap around some of the numbers, but it would still require a minimum of 3 numbers to get all the information.

Something like:
195-630-380?
Width, diameter, wheel diameter?

Bearings and all similar hardware is just spec'd as [inner diameter] x [outer diameter] x [width] all in the same units

Super easy, maybe I'm missing something but I'm not sure why tire companies couldn't just do the same

cyphersBearings and all similar hardware is just spec'd as [inner diameter] x [outer diameter] x [width] all in the same units

Super easy, maybe I'm missing something but I'm not sure why tire companies couldn't just do the same

At this point it's just a trade size. Same reason a 2x4 isn't actually 2" x 4". Or how 1" PVC pipe isn't actually 1" diameter.


Found a super interesting summary for the reasoning behind this system.

"One key fact is that the U.S. has traditionally been a dominant world market for tires. The U.S. Department of Transportation got to set the original nomenclature for tires. That's why, until the 1960s, the wheel size was in inches, the tread width was in inches and there was no sidewall height information (the percentage known as the "aspect ratio"). Back then all tires had the same aspect ratio, which was 90.
But then, technologically superior radial tires were invented in Europe, and the Europeans wanted to sell their tires in the huge U.S. market. And since the only legal requirement for selling tires in the U.S. was that the wheel size be stated in inches (because consumers didn't care back then how wide a tire was), the Europeans just had to change that one number on their tires, and bingo! They had access to the world's largest tire market at the time.

Radial technology also allowed for wider tires and shorter sidewalls. That's when you started seeing aspect ratios on tires. And I'm guessing that, at some point, the U.S. and the U.K. were such dominant car markets that the European manufacturers just said "OK, Uncle!" and started using inches for wheel size in Europe, too. Because if you check out tires sold in Europe, the vast majority have the same nomenclature that we use here."


TLDR: US decided rim size, Europe decided width and aspect ratio

No.Quarterwhoever decided tires sizes should be designated as they are was on crack

I agree. Aspect ratio is a stupid measurement to put in the size. Almost as bad as having multiple units of measurement. Width, diameter, and rim size. It's annoying AF to have to scroll through all the specs to find out what the diameter is on a particular size. Your average person probably has 0 concept of what a tire size means, and I don't blame them.

No.Quarterwhoever decided tires sizes should be designated as they are was on crack

I got a stroke trying to comprehend this post

Chron_RabbitI got a stroke trying to comprehend this post

lol you're welcome

If I understand right you are just moving from a 15” to 14” rim, the first two numbers are like something equating to height and width so the overall outside size of the tire sounds the same. I guess I would just verify that the rims actually fit on your lug pattern.

Update: the rims fit nicely, wheel turned freely, I heard a little scraping but on closer inspection it was just the brake drum was a it loose. However, I found another good set of snow tires that are 15s, only difference is they're 10 mm wider but they are also studded, so I'm going to have those swapped with my all seasons instead.
Thanks for all the responses!