Larger Wheels and Shallower Tires (of course), negative effect on braking performance ?
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Larger Wheels and Shallower Tires (of course), negative effect on braking performance ?
I was doing some spirited driving recently and realized the turn I needed to make was a lot closer than I'd expected it to be, so I was really heavily braking and it seemed to me, that my braking performace is now worse than it was before I upgraded from 17" to 19" wheels. Was it my imagination ? It's the only time I've had to slam the brakes on pretty hard recently, so it could be just that they're getting closer to needing new pads/discs than I thought.
Or is there some science to it? That having lower profile tires does in fact negatively affect braking. They flex less, which may be a good thing, or a bad thing. I'm not sure. On the positive side though, I've now got 10mm more contact with the road since these tires are 245 and my 17's were 235.
Or is there some science to it? That having lower profile tires does in fact negatively affect braking. They flex less, which may be a good thing, or a bad thing. I'm not sure. On the positive side though, I've now got 10mm more contact with the road since these tires are 245 and my 17's were 235.
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Depends on the weight of each tire/rim set up and how that weight in distributed.
Short answer: you're probably not imagining anything. If the 19's are the wheels in your sig pic, IIRC those things weigh a ton.
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So not specifically the wheel size or tire height as such, just the extra weight probably
I think I had a full tank of gas, had some stuff in the back, some leather cream soaked into the seats after my recent pro-valet, and I was carrying a lot of speed, and yes those wheels are heavy. Probably a good thing I went for the 93Y load rating rather than the 91's I was initially offered (from the wheel retailer).
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Shorter sidewalls improve response, at the expense of ride comfort. Otherwise it comes
down to rotational mass and unsprung weight. It's like trying to trying to run a race wearing logging boots vs track shoes.
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Re: rotational mass
So if I understand the meaning of the rotational mass being mentioned, the idea must be that adding (for example) 40 pounds to the car via 10 pounds per wheel with heavier wheels, is a lot different to having for example a 40 pound child on-board as a passenger.
The point being that the rotation of that extra wheel weight has it's own momentum that resists being slowed down, and has little really to do with the fact that the car itself has momentum. It would of course be noticeable if I was doing a brake test on a rolling road.
So it's not so much that the extra weight of the car due to the heavier wheels is the problem. It's that the wheels being heavier means that once they get rotating, they don't want to stop rotating. So I'm much less likely to lock up the brakes and trigger the ABS, because the wheels don't want to stop rotating.
I think I get it now. Or I completely misunderstood
I guess to some extent, this can mean I could freewheel further if I switched to neutral :-)
The point being that the rotation of that extra wheel weight has it's own momentum that resists being slowed down, and has little really to do with the fact that the car itself has momentum. It would of course be noticeable if I was doing a brake test on a rolling road.
So it's not so much that the extra weight of the car due to the heavier wheels is the problem. It's that the wheels being heavier means that once they get rotating, they don't want to stop rotating. So I'm much less likely to lock up the brakes and trigger the ABS, because the wheels don't want to stop rotating.
I think I get it now. Or I completely misunderstood
I guess to some extent, this can mean I could freewheel further if I switched to neutral :-)
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You got it! That's exactly the point! Also, because the shocks and springs are trying to
respond to irregularities of the road via the wheel/tire, they may sometimes be overwhelmed by the extra weight of larger or heavier combos. Even a larger wheel of the same weight as stock, may be a decrease in performance, since it is likely that more weight will be concentrated towards the rim.