Bridgestone Announces Large Diameter Narrow Tires

[freebeard]

Search results for: '19" wire wheel'

What I want are Bridgestones on red Ford wire wheels under my Dove Blue panel van. But they're US$505-525 in primer!

I could sell the Rader mags but they'd only bring in half that.

$515x4 plus $260x4 is $3100 without mounting, balancing and alignment. Unless you want a spare [$3875].

I'm hoping they optimized the edge of the tread to minimize wheelwell turbulence.

[TexasCotton]

Originally Posted by sidecar

Ive been looking over a few older threads, there seems to be a popular disconnect.

Over at the prius forums people have been experimenting with larger than OEM rims (but important to stress same rolling diameter) just for the 'looks' of it. The experience is, that even with tyres with good RR data, the fuel economy rises some 3-4 mpg shifting up from the very light 15" OEM wheel to something in the area of 17-18" diameter rims.

The problem is, we have been unable to establish a common RR formula for both standard size and larger diameter tyres. We have been unable to

It always seemed logical to me that very small sidewalls would create a lower weight tyre, which would offer better sidewall control, and therefore better mileage. But experience has proven this to be flawed, and I think because as lower tyre weights are apparently more than offset by heavier wheels. Add to that generally taller wheel diameters always seem set to wider than conventional rims, generally adding to the aero drag and generally behaving different to stock diameter footprint.

This could also mean, you might be tempted to do this for the additional contact patch at similar psi. IOW reasons of safety in more marginal driving conditions. Which is ok, options are good, but it isnt a like with like comparison if fuel economy was of interest to you.

We also found that, it mattered if summer or winter driving conditions, but have been unable to establish if this is because the tyres themselves are warmer and less brittle on the road or if winter driving conditions just made general fuel economy suffer.

I think we desperately need to know some things, like a common RR for tyres of different diameters. And establish rim/tyre combos that come out as near equal weights. Only then will this argument be scientifically settled. But the fact remains is that despite this thinking, practical experience proves that larger diameter wheels fitted with suitable low profile tyres of the same rolling diameter will increase MPG in the area of 3-4 MPG.

I guess or assume you overlooked the horror story thread about a GEN 2 Prius owner that went from the stock oem 15 to a larger wheel/rim size and decreased their mpg. I take issue with your statement about a mpg increase on non stock oem 15 inch rims ......unless you can give more veracity to your previous statements. I have yet to see a toyota prius gen1,2 and 3 owner document any mpg increase with non stock oem rims...!!!!!!!

[TexasCotton]

Originally Posted by P-hack

And well I suppose there is this to think about too with truck like inflation pressures and narrow tires:

what psi do you have/use on your 15inch p185/65 oem stock tires in your Gen2 Prius

[Thenorm]

Originally Posted by NeilBlanchard

Some more information about these tires on the BMW i3:

More Details on the BMW i3 Bridgestone Ologic Tire Technology | Inside EVs

i get conflicting info in that article.

it mentions low deformation for LRR, but then mentions long contact patch. A long contact patch would require deformation of the tire.

so, what do we really have. Is this a one or the other condition? inflate tire for LRR or deflate for higher traction performance?

[NeilBlanchard]

No, a long contact patch is just what happens geometrically with a large diameter tire.

[Thenorm]

if we assume contact patch is governed approximately by air pressure.
and we use some random numbers.
due to x load and y pressure, and z circumference. same in both cases.
a 10" wide tire deforms 2" of the tire circumference giving 20 sq inch of contact patch
a 4" tire will have to deform 5" of circumference to support the same load at same pressure.

i argue that 5" is greater than 2" of the circumference of the tire that has to deform to conform to the flat road. for tires of equal diameter

[Frank Lee]

if we assume contact patch is governed approximately by air pressure.

Can't do that; it doesn't work that way.

[RedDevil]

The contact patch area size is by and large a result of the weight on the wheel divided by the pressure in the tire, although tire construction does influence it too.
If you make the tire both larger and skinnier the patch will be longer and narrower.

The sidewall deformation of the tire will be less than it would be on a contact patch of similar length on a smaller wheel, but slightly larger than on a smaller but wider wheel with the same contact patch area size.
Thread deformation would be respectively much less and equal.

Scaling up size, width or pressure reduces deformation, all else kept equal.
When you compensate one with the other then it roughly equals out.

[CapriRacer]

OK, guys, I need to correct some misconceptions:

1) You can NOT calculate the size of the contact patch using inflation pressure and load. It doesn't work that way. Here's a link to a proof:

Fact or Fiction? Tire contact patch and air pressure.

I've also noted other studies in this web page:

Barry's Tire Tech

2) I think the "long" is a relative term - meaning, "Instead of a short, broad contact patch, these tires have a long, narrow contact patch." - and that makes sense in the context of a larger diameter, but narrower tire.

[Hersbird]

No matter the size or shape of the patch, the pounds of the car don't change, and so the traction is the same. Race cars use as large a contact patch as possible for heat control. These tires here aren't really large diameter, they are standard diameter, just skinny and with a low sidewall profile.