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Hello , Iam new at this site, however I have found it most helpfull in all questions i have wanted too know, To the point now, I bought a 95 sl320 which is the finest auto that i have ever owened! what i do not understand is the young folks wanting to change to bigger rims such as changing from the stock 16" rims too larger? Is there a reason in preformance and or handling ? or is it done for gas milage. thank you for all the wisdom. n.j horst.
 

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BenzWorld Tire & Wheel God
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performance, handling and asthetics are all reasons to upgrade wheels and tires on a vehicle ... but each has a price .... and larger wheels have a firmer ride
 

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performance, handling and asthetics are all reasons to upgrade wheels and tires on a vehicle ... but each has a price .... and larger wheels have a firmer ride
I have wondered about this too.

I can understand the aesthetics and I guess the firmer ride is because the reduced height of the tyre wall means less "bounce" in the tyre.

I have also been told that you get more road noise from larger tyres. Is this correct? Why?

Can you also explain the actual performance and handling differences?

Many thanks, Tom
 

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I have wondered about this too.

I can understand the aesthetics and I guess the firmer ride is because the reduced height of the tyre wall means less "bounce" in the tyre.

I have also been told that you get more road noise from larger tyres. Is this correct? Why?

Can you also explain the actual performance and handling differences?

Many thanks, Tom
Hi, Tom.

All other things being equal, a larger tire provides a larger contact patch. That in turn increases the amount of frictional force that can be attained between the car and the road in all dry road conditions (starting, turning and stopping). (Let's leave inclement weather out of the picture, we're on basics here.)

Of course if you have a larger contact patch that will increase road noise by some measure. On some cars -- and this is much more rare -- a wider tire will also result in more wind noise, although this is usually also perceived as road noise.

Increasing the wheel size effectively decreases the sidewall height, typically leading to a harsher ride. However, the benefit here is that the larger contact patch combines with less sidewall flex, meaning crisper handling as you turn the wheel. Aside from a harsher ride, small aspect ratios in areas with poorly-maintained roads can result in bent or broken rims from potholes, etc.

As a very broad rule of thumb for passenger car tires, once you decrease the aspect ratio below 45 there is a pronounced increase in ride harshness. As you move to 70 and beyond there is a noticeable loss in "road feel" and an increase in the "floating" sort of mushy feeling. So aspect ratios in the 45-65 range are the general compromise area.

If you're old enough to remember bias-ply tires, they were mostly all 75-85 aspect ratio in part because their construction made for a stiffer sidewall, so you needed more sidewall to have a comfortable ride. One of the many benefits of radial tires is that the ply construction helps provide a smoother ride with a shorter sidewall, thus improving ride and handling simultaneously.

Hope that helps make a bit more sense of it all.

Take care and enjoy the ride,
Greg
 

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Thanks Greg that was just what I wanted!

I've tried searching for this info but it is difficult to find the right search terms that don't just return an explanation of tyre sizes.

Sadly I became a MB owner as the result of "inclement weather" when I lost control of a Volvo V70 on melting compacted snow and ran head on into a brick wall. Fortunately I was only doing 20mph at the time and nobody else was involved but £7000 damage to the car (the wall was unmarked - I bounced off it like a pinball) was enough to see the end of a car the whole family had grown very attached to.

I had always assumed that larger tyres were better for all situations but subsequent reading and my own experience has taught me better :crybaby2:

Thanks once again for your detailed explanation,

Tom
 
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