lost of stopping power after tire upgrade

[renep74]

Hi everyone,

I just finish putting the FC cruiser wheels and tires (265/70/17) and test drove the truck. I notice that the truck takes longer to stop compared to the stuck tire (265/65/17). Is this normal for a bigger tire or there is something wrong.

265/65/17 --> original tire

265/70/17 --> new tire size (with FJ cruiser wheels)

Thanks,

Rene

 

[NJshadow93]

Hi everyone,

I just finish putting the FC cruiser wheels and tires (265/70/17) and test drove the truck. I notice that the truck takes longer to stop compared to the stuck tire (265/65/17). Is this normal for a bigger tire or there is something wrong.

265/65/17 --> original tire

265/70/17 --> new tire size (with FJ cruiser wheels)

Thanks,

Rene

That's normal. I'm sure you noticed your speedometer is off a bit too. If not, use a GPS and take it out on the highway, it will be about 2-3 mph off.

 

[mikebontoft]

no surprise here.

 

[renep74]

NJshadow93/mikebontoft,

Thanks for the quick reply, also for reminding about the speed difference. I'll use the GSP tomorrow when going to work to get use to the new speed.

Did you notice any major gas consumption after the your tire upgrade.

Rene

 

[riceandpho]

when was the last brake job performed?

 

[renep74]

Last spring, change brake pads. also planning to change or rebuild front calipers, when I have the time this summer.

The truck was braking properly before the tire upgrade, i just notice the braking difference after the upgrade.

 

[riceandpho]

unless you are low in fluid, or theres air in the lines. you shouldnt have a problem, just check how much life is on the pad too.

 

[ebg18t]

Heavier larger tires will require more braking force.

 

[honda_nos]

When I changed the Limited 18s 265 60 18 out with 17s 265 70 17 I noticed no major difference. Of course, my Level 8s are likely lighter than the factory wheels.

 

[riceandpho]

What brand tires? It shouldnt be much differnt in stopping power unless you have some heavy rim and tire combo, i have about 95 pounds on each corner and it stops fine, i do have bigger brakes since its a sports model, but also i use ebc yellow pads and drilled and slotted rotors.

 

[renep74]

michelin LTX A/T2 (t4r limited).

 

[ridefast]

With stock tires our spedo reads about 3-4 mph fast at highway speed i bet with the one series bigger tire you will be reading spot on with an ultra gauge or gps.

 

[MikeInNH]

The new tires are going to be a little taller...but not so much that they'll effect braking that much. I'm surprised that there's much of a difference.

 

[M1911]

Bigger, heavier tires have more rotational inertia. As a result, they require more power to accelerate and more power to brake.

 

[MikeInNH]

Bigger, heavier tires have more rotational inertia. As a result, they require more power to accelerate and more power to brake

Agree...but the new tires are not much bigger. If you do the math and figure out the volume difference you're talking about 2% difference in total volume...so there really shouldn't be that much of a difference.

 

[M1911]

Agree...but the new tires are not much bigger. If you do the math and figure out the volume difference you're talking about 2% difference in total volume...so there really shouldn't be that much of a difference.

The issue isn't volume, it is moment of inertia. More weight farther from the center of rotation greatly increases moment of inertia. How much heavier are the new tires and how is that weight distributed?

 

[renep74]

I drove to the office today and notice on my lie-o-meter (APG, reset after the tire upgrade test drive). My APG when up by 2 and started to go back to normal.

I'll keep you posted on what will be my mileage for my full tank. Previously, my full tank (20 gal) is usually 320 - 330 city driving.

 

[blk-4runner]

Same thing happen to me, I went from 265/65r17 to 265/70r17 then to 315/70r17.

 

[MikeInNH]

More weight farther from the center of rotation greatly increases moment of inertia.

And the difference between the 265/70 and 265/65 is less then half an inche...So again I don't see how it'll make ANY noticeable difference.

 

[NJshadow93]

Personally, I didn't notice a difference in acceleration or braking power, not even a little. The only thing that changed was my speedometer accuracy.