Does wheel width affect tire speed
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Does wheel width affect tire speed
I recently swapped out my stock 18” wheels that are 7.5” wide for 18” wheels that at 8.5” wide and kept my stock tires. Will the width change affect the tire diameter? It may be an optical illusion but the tires seem to sit lower than the same tires on the 7.5” rim.
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In a very slight only seen by a tape measure kind of way. I doubt it's more than a 1/4" diameter difference.
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265/60R18 is the tire size. Before and after since I re-used the same tires.
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If there was any change, I would expect the new setup to be ever so slightly taller...but I would also expect it to be nearly imperceptible.
Your 265mm tread width is approx 10.4”, which is wider than your wheel. So, by going to an 8.5” wheel, which is closer in width to the tire (than the 7.5” wheel width), the sidewall should become a wee bit more vertical...that should make the new combination a tiny bit taller.
Your 265mm tread width is approx 10.4”, which is wider than your wheel. So, by going to an 8.5” wheel, which is closer in width to the tire (than the 7.5” wheel width), the sidewall should become a wee bit more vertical...that should make the new combination a tiny bit taller.
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If there was any change, I would expect the new setup to be ever so slightly taller...but I would also expect it to be nearly imperceptible.
Your 265mm tread width is approx 10.4”, which is wider than your wheel. So, by going to an 8.5” wheel, which is closer in width to the tire (than the 7.5” wheel width), the sidewall should become a wee bit more vertical...that should make the new combination a tiny bit taller.
Your 265mm tread width is approx 10.4”, which is wider than your wheel. So, by going to an 8.5” wheel, which is closer in width to the tire (than the 7.5” wheel width), the sidewall should become a wee bit more vertical...that should make the new combination a tiny bit taller.
The more you squish the tire together, the taller it will be.
So the same width tire on a narrower wheel will be slightly taller since it has to squish together more to sit in the bead of the narrower wheel.
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It always helps to use exaggerations in things like this. In your head, imagine the bead cannot be lost and is permanently fixed to the wheel. take that wheel and expand it out widthwise an inch at a time. As the wheel gets wider, the sidewall will start to become more horizontal with each inch, thereby reducing the tread elevation slightly with each inch. Reverse similar, if the wheel width were to be condensed down to say an inch wide pulling the shoulders down first and eventually the tread down with it to stay with the shoulders. There is a sweet spot in the middle where you will have maximum tire height.
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Thanks for all the responses. I just took my son out and did a non-scientific test to see if my speed would be off with the change. (My son should be an expert with speed, give his recent history with obtaining speeding tickets.) 
I used the speed shown on a GPS unit to compare against my speed set w/ cruise enabled. At all intervals, they were a dead on match. So either the change is minimal and isn’t affecting my speed or the GPS is off by the same amount as the change in tire size. I’m pretty sure the correct answer is there is negligible tire size difference and my speed is not affected. Thanks everyone!
I used the speed shown on a GPS unit to compare against my speed set w/ cruise enabled. At all intervals, they were a dead on match. So either the change is minimal and isn’t affecting my speed or the GPS is off by the same amount as the change in tire size. I’m pretty sure the correct answer is there is negligible tire size difference and my speed is not affected. Thanks everyone!
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Apparently, we are all wrong.
There is no change in overall diameter when a tire is mounted on a wheel that is within the approved range for the tire...according to Tire Rack. That doesn’t address puttting tires on wheels that are outside of the approved range...but the OP isn’t asking about that.
Frankly, I was surprised, because it isn’t what I expected.
Per the article: The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim. Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width
link: https://tires.tirerack.com/search?p=...core&view=list
There is no change in overall diameter when a tire is mounted on a wheel that is within the approved range for the tire...according to Tire Rack. That doesn’t address puttting tires on wheels that are outside of the approved range...but the OP isn’t asking about that.
Frankly, I was surprised, because it isn’t what I expected.
Per the article: The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim. Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width
link: https://tires.tirerack.com/search?p=...core&view=list