Re: Sales Are Way Off, Could It Be the Tires?

A few comments: (1) Low profile does not automatically (and very seldom does it) mean a wider tread. Besides, tire manufacturers finally learned that they can design sipes and wide circumferential grooves in the treads to solve the hydroplaning issue. For some reason, they were pretty stupid about the obvious for many years. Nowadays (is that a word?) wider does not mean inherently susceptible to hydroplaning with half-way intelligent tread design. (2) One advantage of larger wheels and lower profile tires is that for a given tire OD, the brake rotors can be larger - that may be one of the main drivers to the larger wheels, as attaining problem-free brakes seems to be a problem on many (most?) cars these days. One of the first mods I did to my Concorde was to go from 15 to 16" wheels so that I could convert it to the larger factory rotors - the LH cars really need those. (3) One of the biggest downsides of larger wheels is that the rotational moment of inertia is greater, so straight line acceleration suffers. (4) Another downside of larger wheels is that tires are priced like bikinis: As the amount of material in them decreases, the price increase exponentially (compare prices of 15, 16, 17, 18, 19 inch tires and you will see what I mean). (5) As far as the harder ride with lower profile: That can be partially compensated for with suspension and spring design, although unsprung weight cannot be compensated for no matter what - and that contributes to harsher ride.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

No offence, but I do not like the image of my Bonnie with 14 inch -80's tires.

I have 70 on my Concord, I believe my wife has 65 on her Sybring. I feel the 70s are the best compromise. My cousin has a Volvo with very low profile tires. The only difference I've noticed is a harsh ride on breaks in the pavement.

Yes extremely low profile on street cars is just styling IMO.

-Worse for hydroplaning all things being equal, harsher ride, more tires and rims damaged from potholes. It has been mentioned that hydroplaning can be made to equal a regular tire, but I disagree on the conditions I sometimes experience. Like going up a steep mountain road in heavy rain with a stream of water coming down in the depressed from traffic roadway- just like driving up hill on slick ice. I found a 70 tire that will handle this, but noticed some all season treads from the same manufacturer that obviously wouldn't.

-They require much more spare wheel well height, so many cars have a much narrower spare and can't take the flat tire in in the spare well.

They are extreme styling. Many vehicle models are still available with

You are going too far back with 75+ profile.

Why is everyone insisting on keeping "everything else equal"? There is nothing - absolutely nothing - inherently more hydroplane-susceptible about low profile per-se if the tire is sized properly with the lower profile. I'm not into the extreme either (I have 60's on my Concorde, and that is "extreme" as I want to go), but when one goes to a different size (larger wheel & lower profile), one simply specs the numbers to maintain the same tread width ( => hydroplaning susceptibility) and tread OD (speedometer/odometer reading).

You could go to smaller OD and *still* maintain the same tread width (hydroplaning resistance) if you wanted to. There's no reason one couldn't go with larger wheel, lower profile, *and* narrower tread if hydroplaning is the concern while maintaining speedo accuracy - absolutely no reason.

It's ridiculous to list worse hydroplaning as an inherent property of lower profile - because there's no reason to keep "everything else equal" - the conversion charts reflect that.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Lots of folks have been surprised at how fast the -50 and lower profile tires often wear and how easy it is to do massively expensive rim damage. Ask any Volvo 850R owner!

John