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Re: Pothole queen tire thread

Lloyd E Parsons
SubjectRe: Pothole queen tire thread
FromLloyd E Parsons
Date02/28/2014 14:19 (02/28/2014 07:19)
Message-ID<bnbgn8FscsfU1@mid.individual.net>
Client
Newsgroupscomp.sys.mac.advocacy
Follows-hh
FollowupsDavid Fritzinger (36m) > Lloyd E Parsons
-hh (1h & 36m) > Lloyd E Parsons

On 2014-02-28 11:48:42 +0000, -hh said:

-hh
I hate front wheel drive, send most torque to the rear, please wrote:

I hate front wheel drive, send most torque to the rear, please
Pothole resilience is more dependent on how thoroughly sidewall is designed on a particular tire model.

-hh
Agreed, although there's also crossover into the tire diameter and rim size, as these determine "how much room" you have to work with for your sidewall design. Plus other factors such as what effective spring rate the sidewall design is intended to have.

I hate front wheel drive, send most torque to the rear, please
(I guess) the lower you go in profile though>the more manufacturer tries to save on sidewalls to keep the tire weight down so (I guess) 2 ply sidewalls are rare if at all obtanium on semislick 30-35 profile rubber bands.

-hh
IMO, it is not a "materials cost" question.

The tire dimensions affect tire patch area, which influences handling performance. Similarly, the sidewall also influences performance ... one can see how a shorter & stiffer sidewall would make things more rigid - - and less movement of the tire patch relative to the vehicle (a "less wiggly" tire).

However, going to a smaller sidewall carries connotations that there's less distance for elastic defection from impacts (e.g., potholes) and a stiffer sidewall similarly makes it more prone too (less pliable = less likely to be as fully elastic across the same range, etc).

I hate front wheel drive, send most torque to the rear, please
(I guess) its the exact same deal with haldex "awd": the crap does not work (well if at all), but, since populace>is not particularly sophisticated, manufacturers get away with it.

-hh
Yup. Another factor is product styling - - there's a good number of consumers who prefer the appearance of larger rims / smaller sidewalls without appreciation of their trade-offs.

I hate front wheel drive, send most torque to the rear, please
If you go far enough in the past 80 was considered "low profile" but I guess you'd be hard pressed to find 80s and 90s outside the trucks domain today.

-hh
Yes, an 80 sidewall on a US automobile (not truck) would be ancient. Recent vintage stuff here - especially anything that even smells of performance is usually all below a 60, particularly since rim sizes have gone up. For example, one of the tire sizes that I'm running right now on one of the vehicles is a 225/45R17 and if I were to mention that at a social gathering, I'd probably have no one blink at the 45 sidewall ... they would be more likely to comment about the 17" rim being "small" and that they're running a 19" or 20" ... maybe even a 21" rim. Granted, such casual comments usually ignore differences in overall wheel/tire OD, so the amazing shrinking sidewall issue isn't quite literally so extreme, but they're certainly not as tall as they were some years ago, which in conjunction with our degraded infrastructure is resulting in more blow-outs and damaged rims ... BTW, this is also something that is being made worse by "Run Flat" tires, as they have even stiffer (less forgiving) sidewalls: I have one colleague with a ~2011 BMW 335i who in the first two years that he owned the car, had IIRC ~7 run flat tire blowouts and 4? damaged rims. Thank you BMW for a ridiculously small 35 sidewall (30 rear) coupled with a stupid tire design on what's supposed to be a "Daily Driver". For the operating expense of this, figure roughly US$600 per tire after the new car's supplementary two year tire insurance policy ($2000+) expires. Oh, and the wheels are usually not well covered by such policies, so he had to spend another $2K out-of-pocket for four replacement rims.

-hh

A popular size these days seems to be 235/45R18, saw it on lots of cars while I was looking and is what is on the Verano.

But they sure don't cost $600 apiece!! :) Around $200 each is more like it. Of course, with a blowout the odds of wheel damage are heightened so add in at least another $400+ each for that.

Even at those somewhat lower prices, it is fucking ridiculous for something less than a full blown racer for tires and rims. Contemplating the cost of replacing them makes me fondly remember 78 and 80 tires, plain rims with old style hubcaps!! :)

Seems those higher sidewalls are gone now, or nearly so. Hell, even pickup trucks don't have them much these days, also opting for fatter tires and taller rims.

The story is that it is to help with fuel mileage as the rim material is lighter than the tire material. It used to be that you got the upscale rims/tire configs on cars further up the food chain, but not so these days where even many of the very low priced ones have these configurations.

-- Lloyd