dss00@amdahl.UUCP (dss00) (07/26/85)
I just bought 4 new tires for my Accord. As usually happens with
most of my purchases, I have a few questions about what I bought
after the fact.
The tires are Michelin MX, Size P175/70R13. I have the following
questions, and would appreciate answers from any one in the know.
1. The original tires were size 155SR13. The tire dealer said that
P175/70R13 are acceptable size replacement for 155SR13. As far as
I know, the main difference is the 175 mm width of the new tires
as against 155 mm width of the old ones.
What I am not sure about, is the overall size (outer diameter)
of the new tires compared to the old ones ?
It may affect the speedometer/odometer.
2. After I drove home, I noticed that two of the tires are made in
U.K. and have marking "P175/70R13 82T", where as the other two
are made in W. Germany and have marking "P175/70R13 82S".
My question is - what does the 82S and 82T mean? Does it have any
bearing upon the rating/performance/life of the tires? Also, is
it necessary to have the tires with identical markings on
the same axle (at present they are not, each axle has one 82S and
one 82T)? The tires are identical otherwise i.e. the traction grade,
temperature grade, tread design and all other markings are identical.
Any help would be appreciated.
Incidentally, the tires are no longer marked for tread wear rating, nor
do they carry any tread wear warranty.
--
Deepak S. Sabnis ...!{ihnp4,hplabs,amd,nsc}!amdahl!dss00 (408) 746-6058
(Usual Disclaimer Here)mayer@rochester.UUCP (07/26/85)
From: Jim Mayer <mayer>
I have a few questions about automobile tires. The (hypothetical) car
in question is a small front wheel drive model. Any tires I bought would
almost certainly be steel belted radials.
1. Does anyone know a good source of information about tire
performance beyond the US (Traction/Heat/Treadwear) ratings?
2. How good are all season tires vs. snow tires? Rochester gets
regular (usually light) snow in the mornings (courtesy of lake
Ontario) and one or two real snows each year. Should this
affect the kind of tires I buy?
3. If I get real snows, is there any advantage to outfitting all
four wheels?
4. How good are all seasons vs. regular tires during the summer?
Are they as quiet? Do they handle as well?
5. The cars I've looked at all come with only so-so tires
(US rating B/C). I figure if I'm going to shell out $10000
or so for a car, I can afford a few hundred more for a set of
really good tires. What's the best way to sell the original
set? How much would I be ripped off if I traded them in?
Thanks.
-- Jim Mayer University of Rochester
(arpa) mayer@Rochester.ARPA Department of Computer Science
(uucp) rochester!mayer Ray P. Hylan Building
(via allegra, decvax, or seismo) Rochester, New York 14627steve@mtu.UUCP (Steve Seidel) (07/29/85)
In article <1839@amdahl.UUCP> dss00@amdahl.UUCP (dss00) writes: > >I just bought 4 new tires for my Accord. As usually happens with >most of my purchases, I have a few questions about what I bought >after the fact. > >The tires are Michelin MX, Size P175/70R13. I have the following >questions, and would appreciate answers from any one in the know. > >1. The original tires were size 155SR13. The tire dealer said that > P175/70R13 are acceptable size replacement for 155SR13. As far as > I know, the main difference is the 175 mm width of the new tires > as against 155 mm width of the old ones. > What I am not sure about, is the overall size (outer diameter) > of the new tires compared to the old ones ? > It may affect the speedometer/odometer. A booklet I got from Euro-Tire, Inc. (an aftermarket mail order tire outlet that advertises every month in C/D) lists the approximate overall diameters of 155SR13 and 175/70R13 tires as 578 mm and 580 mm, respectively. These figures surely vary from one brand to the next and precise numbers depend on other variables like inflation pressure and temperature. But that was as true for the old tires as it is for the new. Your speedometer/odometer should not be affected. Can't answer your other question, but I do have an aside to add to the controversy about tire inflation pressures. I and lots of other people regularly inflate their street legal tires to pressures in the neighbor- hood of 50 psi for autocrossing. Heat buildup is not an issue since speeds seldom exceed 40 mph during a run, and then only for a few seconds. I have never seen a street tire rated above 36 psi maximum inflation pressure; the implication I draw is that street tires won't blow up if you overinflate them a bit. Nobody would want 50 psi for the street, but I sometimes run 36 - 38 psi with no immediate ill effects. -- Steve Seidel Michigan Technological University uucp: {lanl, ihnp4, glacier}!mtu!steve arpa/csnet: steve%mtu@csnet-relay
wjh@bonnie.UUCP (Bill Hery) (07/29/85)
> I have a few questions about automobile tires. The (hypothetical) car > in question is a small front wheel drive model. > .... > 3. If I get real snows, is there any advantage to outfitting all > four wheels? > If you only get two, they should go on the front for a front wheel drive car; they will improve tration for straight lne acceleration and braking. An additional pair of snow on hte rear wheels will help during turns; without them, the car will have more of a tendency to spin out on snowy curves, particularly if it has a very light rear end. This is particularly true if you get studded tires, where the big difference in traction will make the car unstble on snowy/icy turns.
geoff@denelvx.UUCP (Geoff Baum) (07/29/85)
> From: Jim Mayer <mayer> > > I have a few questions about automobile tires. The (hypothetical) car > in question is a small front wheel drive model. Any tires I bought would > almost certainly be steel belted radials. > > 3. If I get real snows, is there any advantage to outfitting all > four wheels? Having done lots of winter driving in small front wheel drive cars, I would offer the following advice: DEFINITELY OUTFIT ALL FOUR WHEELS! I have driven Honda Civics, Saab 96s and Saab 99s in rain, on snow, and on ice. The often used tactic of putting snow tires only on the front wheels can be dangerous. This is especially true if you use studded snow tires. What happens is the following: Studded snow tires on front wheels, summer tires on rear wheels. This has the affect of providing much better traction for the front wheels than the rear wheels, when driving on icy roads. This means that any sudden steering or braking will cause the rear of the car to lose traction and slide. Since the front wheels are still gripping the road, the rear of the car will quickly spin around the front of the car and you will find yourself traveling down the highway backwards. The worst part of all this is that the above scenario may never happen EXCEPT in an emergency as the result of a sudden manuver. In other words, just when you need to be able to control the car the most, you lose control. Whatever tires you have on your car, it is best to have the same ones front and rear for the above mentioned reason. Personally, I never felt the need for snow tires in New England. Front wheel drive gives plenty of traction in winter conditions. I always took side roads when the weather was bad, so I didn't have to worry about people going 60 mph down an icy highway. Here in Colorado, however, I have to drive 30 miles of highway to get to work, so I have studded snows all around. They allow me to brake faster on ice. The studded snow tires have several disadvantages which should be carefully considered. 1) They enable you to stop faster than most people on the road (often an advantage) which means that you have to watch your rear view mirror carefully, and start braking early so that the person behind you will be able to stop before ploughing into you. 2) They excellent traction they provide keeps you from knowing what other drivers are experiencing. This could cause you to misjudge the behavior of other drivers on the road. The real advantage in not using winter tires is that you know exactly what the conditions are, and will drive accordingly. I think this is the best way to go unless you must drive (as I must) on roads where people habitually go too fast for the conditions. I do not recommend snow tires without studs. Summer tires are better on dry pavement and in rain. Studded snows are better on snow and ice (actuall, summer tires may be better than most non-studded winter tires on ice). Many people swear by all-season radials. This coming winter will be the first time I will have tried them, so I cannot pass judgement on this particular solution. All I can say is that a friend of mine who always drives too fast swears by them.
geoff@denelvx.UUCP (Geoff Baum) (07/29/85)
> 1. The original tires were size 155SR13. The tire dealer said that > P175/70R13 are acceptable size replacement for 155SR13. > What I am not sure about, is the overall size (outer diameter) > of the new tires compared to the old ones ? > The "70" in "175/70R13" means that the tire's sidewall height is 70% of the tire's width (70% of 175 mm). This number (the 70) is called the aspect ratio. When no aspect ratio is listed, a standard aspect ratio is implied. For 13" tires this implied aspect ratio is 80%. I happen to have written a program which takes all this into account and calculates equivalent tire sizes. It turns out that your original tire and wheel produced an overall tire diameter of 578.2 mm. Your new tires (same wheels) produce an overall tire diameter of 575.2 mm. This is a difference of 0.5% in overall diameter. Since changing one tooth on your speedometer driven gear (the thing that is changed by the manufacturer to accomodate different tire sizes) changes your speedometer reading by about 5%, you can see that you have nothing to worry about. As a matter of fact, I calculate that the normal process of wearing down your tires probably changes your speedometer's accuracy by about 5% also. So, don't worry and have lots of fun. You made the right move. As for the 82S vs. 82T, I have no idea. Geoffrey Baum
levy@ttrdc.UUCP (Daniel R. Levy) (08/03/85)
geoff@denelvx.UUCP (Geoff Baum) <115@denelvx.UUCP>: >I do not recommend snow tires without studs. Summer tires are better on dry >pavement and in rain. Studded snows are better on snow and ice (actuall, >summer tires may be better than most non-studded winter tires on ice). > Has a test of nonstudded "snows" versus summer tires upon ice been published to your knowledge? That could be of concern in a place like Illinois where tire studs are illegal under most circumstances. It's nice to have the "snows" for the real *snow* (more than a couple of inches) but why so horrible on plain ice? (Good summer question :-)) -- ------------------------------- Disclaimer: The views contained herein are | dan levy | yvel nad | my own and are not at all those of my em- | an engihacker @ | ployer, my pets, my plants, my boss, or the | at&t computer systems division | s.a. of any computer upon which I may hack. | skokie, illinois | | "go for it" | Path: ..!ihnp4!ttrdc!levy -------------------------------- or: ..!ihnp4!iheds!ttbcad!levy
review@drutx.UUCP (MillhamBD) (08/05/85)
I read an article in one of the car mags. recently about the difference between regular snow tires, and all season. The outcome was that in loose, freshly fallen snow, snow tires were the best. On ice and packed snow, all seasons were best. Since few people drive on loose snow, they recommended all seasons. I have never put snows, or all weathers on my front drive. I use my Eagle GT's, and drive up into the mountains during a chain law regularly (without chains), and have never had problems. -------------------------------------------- Brian Millham AT & T Information Systems Denver, Co. ...!inhp4!drutx!review