Thinner tires on original rim?

[HydroJim]

When I look at tires, one of the specs is the rim width range. My wheels are 15x5.5 inches, and the stock tires are 195/60R15. I planned on going with 195/65R15 because they are taller tires, but it looks like 185/65R15 will work on my rims also. These are the same diameter as the stock 195/60R15, but they are thinner tires by 10mm. I guess my question is would the 185/65R15's even fit? also, are the 195/65R15 or 185/65R15 better for fuel savings. last, will there be safety concerns with a thinner tire?

[CapriRacer]

The affect rim width has on tire performance is very small provided you stay within the published allowable rim width range.

When it comes to fuel economy, a larger load carrying capacity is directionally better - but the affect is small. So, no, thinner is not better!

But, there is a HUGE range of values for rolling resistance between tires - up to 60%. So careful selection is very important. Just be aware that there is a technology triangle between treadwear, traction (especially wet traction) and fuel economy. Put another way, if you really go after treadwear, the result will not be the best fuel economy.

But with the recent tire price increases, it just may be that we have crossed the point where an improvement in fuel economy - at the expense of treadwear - does not result in an overall cost savings over the life of the tire. Does anyone have the old calculation, so we can update it?

[arcosine]

I have 185/65R15 tires on 5,5 rims and they handle fine, better in rain and snow than fatter tires.

[Ladogaboy]

Just check the rim width range for the tire size you are planning to purchase. The seller should have that information available with the tires.

[euromodder]

Tire Size Calculator - tire & wheel plus sizing
will tell you everything about a tyre size.

5.5 rims will fit either size tyre.

[Vekke]

I will try to make test to put 155/80R14 tire to 5.5" wide rim. Purpose is to get better aero. At least on my Lupo 3L 145/80R14 Bridgestone B381 ecopia vs Nokian hakkapeliitta R 175/70R14 the narrower tire is much better even the Hakkapeliitta R has better LRR factor (is lowest with Michelin XI2)

Wider tire gives much more drag than the RR can give benefit. I will also test 155/65/R14 Hakkapeliitta R later this winter so I know is the aero really the problem or something else. (rims have little bit different ET and are heavier etc...

[BHarvey]

If you look at the specs for each size tire you will see that a 195 can have the same contact patch as some 225's. The size on the sidewall means almost nothing.

[btracing]

On my VW Polo I went from 155/70-13 tires to 135/80-13, on the same original rim (4,5J). It's skinny, but it drives pretty good now. First results I am expecting in en few weeks.

[CapriRacer]

A couple of thoughts:

I've done some calculations of the affect of areo drag vs RR - and found that the increase in aero drag for wider tires is SMALLER than the improvement in RR. I suspect this is because tires are mostly shielded from the wind by the fenders (wings for you Brits!)

Another thought is that, tire size plays a pretty small role in RR compared to the difference that changing tread compound has - that is, different tires (even within the same brand) will have a much larger affect on RR than tire size will have.

[Vekke]

You should also notice that if you put wider tires to your car the tires arent anymore behind the bumber/wings. If they are narrower they might be too much inside...

I think that migh be the biggest reason for my bad fueleconomy with these Nokian Hakkapeliitta R. Should get also different ET rims. There are so many things that affect everything that its difficult say which fault the change is... For Nokian winter tires the outer edge of the tire is sharp and I have thought of grinding it round .

Soon I will have about 7 sets of similar aluminium wheels and will start doing my own winter tire tests which combo works best on my lupo.