Honda Car Forum

In my stupidity, I told the shop that I had a 2000 Civic when I actually
have a 2001 (I got mixed up because I bought the car in 2000). Their
computers automatically look up what size tires they are according to the
year and model, and so they mounted a P185/65R14. It should have been a
P185/70R14. I'm going to go back and see if they'll be willing to exchange
it for me, hopefully I can just pay the mounting costs.

What are the implications of driving on wrong size tires? Is it a serious
safety issue? If my understanding of tires sizes is correct, the difference
between the two tires is in the section heights (185 x .70 = 129.5mm vs. 185
x .65 = 120.25mm). Which would make my car sit about 20mm lower. Also, with
a smaller tire diameter, the odometer mileage would be inflated.

> What are the implications of driving on wrong size tires?

Another issue I thought of was speedometer reading would also be inflated.
According to http://mr2.com/FORMS/tire.html, speedometer and odometer would
be inflated by 3%

I am an idiot.

You'll be fine. 3% is quite moderate. The odometer reading is not much
to worry about, over the expected 50k miles life of the tires the error
would be 1500 miles. As for your earlier math, your car will be riding
only about 9 mm lower, not 20 mm. Distance from center to ground, not
distance from top of tire to ground.

So over the next 50 k miles, enjoy slightly better handling and a
minuscule improvement in acceleration. I went 2% the other way, from
185/60 14" to 195/60 14". No noticeable difference.

DC wrote:
>
> > What are the implications of driving on wrong size tires?
>
> Another issue I thought of was speedometer reading would also be inflated.
> According to http://mr2.com/FORMS/tire.html, speedometer and odometer would
> be inflated by 3%
>
> I am an idiot.

DC wrote:
>
> > What are the implications of driving on wrong size tires?
>
> Another issue I thought of was speedometer reading would also be inflated.
> According to http://mr2.com/FORMS/tire.html, speedometer and odometer would
> be inflated by 3%
>
> I am an idiot.



Naw, that doesn't qualify you as an idiot (I think)... With today's
plethora of choices, I personally wouldn't worry about it.

The 65 series will offer (IMO) slightly better handling but might be a
bit harsher in ride quality.

Of course, if the shop will exchange 'em, go for that but don't lose any
sleep over it if they don't...


--
JT

Just tooling through cyberspace in my ancient G4

DC wrote:

>>What are the implications of driving on wrong size tires?
>
>
> Another issue I thought of was speedometer reading would also be inflated.
> According to http://mr2.com/FORMS/tire.html, speedometer and odometer would
> be inflated by 3%

its usually 3-5% high, so now itll actually read closer to normal.
>
> I am an idiot.
>
>

DC wrote:
>
> What are the implications of driving on wrong size tires?

id prefer what you have. try it, you might like it better. the ideal
"+1" size would be a 195/60 14 for your car, IIRC.

i went from a 185/65 to a 195/60, and it sticks to the road much better.

i didnt know they went to a 70 series aspect ratio... fuel mileage, maybe?

"DC" <noreply@fakeaddress.com> wrote
> In my stupidity, I told the shop that I had a 2000 Civic when I
actually
> have a 2001 (I got mixed up because I bought the car in 2000). Their
> computers automatically look up what size tires they are according
to the
> year and model, and so they mounted a P185/65R14. It should have
been a
> P185/70R14. I'm going to go back and see if they'll be willing to
exchange
> it for me, hopefully I can just pay the mounting costs.
>
> What are the implications of driving on wrong size tires? Is it a
serious
> safety issue? If my understanding of tires sizes is correct, the
difference
> between the two tires is in the section heights (185 x .70 = 129.5mm
vs. 185
> x .65 = 120.25mm). Which would make my car sit about 20mm lower.

Isn't it only about half this much, at 9.25 mm lower?

Yes, the diameter is less by about 20 mm, but it's the radius change
that should equal the height change.

(9.25 mm = 0.4 inches)

Anyway, the trim height (an alignment specification) has now changed.
This affects camber. Camber is the tilt of the tops of the tires away
from the vertical when looking from the front of the car at the tires.
Lowering the car tends to tilt the tires inward. Too much tilt of the
top inward (= excessive negative camber), and tire wear will result on
the inboard side of the tires.

But is this amount of lowering all that much?

Googling at www.groups.google.com for {camber lower civic tire wear}
yields a lot of discussion of this, mostly from guys that hot rod (=
rice?) their Civics. You've lowered the car by a lot less than them,
though. Most of the posts seem to talk about changes of 1 inch or
more. For a drop of a lot less than 1 inch, they suggest you'll see no
adverse effects on tire wear.

E.g. About a 1998 Civic, one guy wrote "you can get away with
virtually no excesive tire wear up to 1.5 inches." Another wrote: "I
guarantee that he will not need an align on a civic for only 1.5 inch
drop!"

You've dropped the car a lot less than 1.5 inches. Doesn't sound like
it's worth losing any sleep over.

I suppose maybe you could get an alignment check and compare your
Civic's camber with its specs, assuming the fact the car isn't the
design trim height doesn't mess up the alignment machine's
calculations and render them meaningless. (I'm not well studied on how
alignment machines work at this point. I do know making sure the car's
trim height is correct is a pre-alignment requirement.)

I'd just keep an eye on tire wear at every rotation.

Agreed about the odometer, but like the other folks said, no biggie at
3%, especially given how much variation there is in fuel mileage from
other effects. I guess if you want to measure traveling distance,
you'd want to make the correction, though.

SoCalMike wrote:

<snip>

> > Another issue I thought of was speedometer reading would also be inflated.
> > According to http://mr2.com/FORMS/tire.html, speedometer and odometer would
> > be inflated by 3%
>
> its usually 3-5% high, so now itll actually read closer to normal.

Wrong way, if it was reading 3% high with the original tires, it will
now read 6% high.

Thanks for everyone's input. It definitely helped to alleviate some of the
panic knowing it wouldn't that that big of deal.

I have to give props to Costco, who exchanged the tires for me without any
hassle, and they didn't even charge me an additional mounting cost. In fact,
the second (correct) set of tires was actually quite a bit cheaper, so I
even got a $40 refund! I guess it was a more popular size or something.

I wonder why Costco tire people wouldn't have noticed that the tires they
put on where not the same size as the old ones.

"DC" <noreply@fakeaddress.com> wrote in message
news:z3ehd.37178$QJ3.13620@newssvr21.news.prodigy. com...
> Thanks for everyone's input. It definitely helped to alleviate some of the
> panic knowing it wouldn't that that big of deal.
>
> I have to give props to Costco, who exchanged the tires for me without any
> hassle, and they didn't even charge me an additional mounting cost. In
fact,
> the second (correct) set of tires was actually quite a bit cheaper, so I
> even got a $40 refund! I guess it was a more popular size or something.
>
>