Nearly 10# unsprung weight increase...

[JHZR2]

Hello,

After 5 years, my tires are starting to look cracked and hard - UV kills them before I wear them out - they have over 50% of the tread, after 42k miles.

Anyway, the tire that was on there, Pirelli P6, weighs 19# each. I am looking at the Bridgestone Potenze RE960AS tires instead, but they weigh 28# each.

The P6 is a widely used OE tire. I think they leep it light and low rolling resistance to help make fuel economy numbers. While I dont have any real complaint about these tires (other then that they are getting cracked and noticably noisier than they originally were), they do get a lot of poor reviews. The Bridgestones get lots of really good reviews, on the other hand... they are heavy, and potentially have higher rolling resistance (combined, ive heard of up to 2MPG loss, but I wouldnt call this scientific in any way).

So, how noticable will 9# of unsprung weight increase be in day-to-day driving? How about when braking? Is it noticable in gentle driving, or just when pushed hard?

Any thoughts would be appreciated.

Thanks!!!

 

[XS650]

Worst case, 9 lb extra unsprung weight will have the same effect on acceleration as 18 lb non-rotating sprung weight. Worst case would be if the weight were all at the outer radius of the tire, which it won't be.

Effects on handling and ride on rough surfaces might be noticeable, probably not very. Changes in ride and handling from differences in sidewall stiffness would prolly be bigger than changes from differences in weight.

 

[d00df00d]

I had the RE960AS on my old Maxima and loved it. In my case, it was 4 lbs per corner heavier than the tire I was replacing (Toyo Proxes 4). I noticed no difference in fuel economy, and everything else including ride quality was significantly better. I can't say what the picture would look like with a 9 lb difference per corner, or compared to a more mainstream tire like the Pirelli P6. However, even if you do notice a difference, I can't imagine it would be anywhere near enough to offset the benefits. The RE960AS is a really, really good tire. It also does exceptionally well in the rain, which I'm sure you'll agree is important.

If you're worried about ride quality with a heavy tire, I can offer that the RE960AS seems to be really good at absorbing and damping bumps. Despite having very robust construction, it looks like it permits small local deformations while maintaining its overall shape. Most tires with softer sidewalls end up behaving more like balloons.

If you're worried about braking, let me assure you that those worries will absolutely evaporate the first time you hit the middle pedal. The RE960AS has so much more traction than the P6 that the weight difference won't matter.

 

[SZR48207]

I went from 285/60/16s to 235/70/16 on my truck. There was maybe 10-15lb difference between the old tire and new tire.

Still drives the same. A LOT easier to turn the steering wheel, though. Of course, the lighter tire makes bumps a bit harsher, but that is expected.

 

[Papa Bear]

You could hammer 9 lbs of wheel weights on the ol' Perellies and take it for a test ride....

 

[JHZR2]

Originally Posted By: XS650
Worst case, 9 lb extra unsprung weight will have the same effect on acceleration as 18 lb non-rotating sprung weight. Worst case would be if the weight were all at the outer radius of the tire, which it won't be.

Effects on handling and ride on rough surfaces might be noticeable, probably not very. Changes in ride and handling from differences in sidewall stiffness would prolly be bigger than changes from differences in weight.


If its not on the outer radius, where is it? Maybe not on the far outer radius, but the sidewall is still relatively far from the hub...

I suppose being heavier out there means more momentum coasting???

What is the basis that 9# unsprung would be like 18# sprung weight? That would mean that the car will feel more or less 80# heavier in various characteristics??? That is an easy enough experiment - I already know the answer!

Thanks!