GC tires - 225/75 vs 245/70 (R16)

The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
I was wondering if the 245/70R16 sizes cause any probs
with speedometer or front turning clearance under the cowling
or any other considerations on going from the 75 to the 70 ?
It seems like the overall outside tire diameter is the same, but ??

Those tires (245-70-16) are listed as acceptable alternates on my 02 WJ to
the stock tires (225-75-16)

There should be no problems



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"Phil Schuman" > wrote in message
. ..
> The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> I was wondering if the 245/70R16 sizes cause any probs
> with speedometer or front turning clearance under the cowling
> or any other considerations on going from the 75 to the 70 ?
> It seems like the overall outside tire diameter is the same, but ??
>
>
>

A consideration ... if you drive in snow, and will be using the 245s they
may be too wide. I say this because the 235 is too wide for my XJ in snow
.... but the XJ is a lighter vehicle I believe (unibody). I use 225 snow
tires ... which unfortunately are due for replacement this coming winter :-(

"Phil Schuman" > wrote in message
. ..
> The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> I was wondering if the 245/70R16 sizes cause any probs
> with speedometer or front turning clearance under the cowling
> or any other considerations on going from the 75 to the 70 ?
> It seems like the overall outside tire diameter is the same, but ??
>
>
>

I will second that. We lost a 'lot' of traction when we went from a 225
to a 235 while keeping the same profile even. Going to a wider 70
series adds to the loss.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Bowgus wrote:
>
> A consideration ... if you drive in snow, and will be using the 245s they
> may be too wide. I say this because the 235 is too wide for my XJ in snow
> ... but the XJ is a lighter vehicle I believe (unibody). I use 225 snow
> tires ... which unfortunately are due for replacement this coming winter :-(
>
> "Phil Schuman" > wrote in message
> . ..
> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> > I was wondering if the 245/70R16 sizes cause any probs
> > with speedometer or front turning clearance under the cowling
> > or any other considerations on going from the 75 to the 70 ?
> > It seems like the overall outside tire diameter is the same, but ??
> >
> >
> >

There will be no difference (OK, the difference will be very small).

The 245 is 20mm wider, that's 10mm off of center, which is about 3/8". This
should pose no particular problem for clearance inside the fenders.

The 70 or 75 represent a diameter change (larger in your case) of 0.4
inches. This will not present any problems for the speedometer or the
gearing. Indeed, your speedometer is about 3 mph fast at 80mph right now,
and will be about 2 mph fast with the larger tires. You will be fine.

The caluclation is
<width -- 225> * <aspect ratio -- 75%> * 2 / 25.4 + <rim -- 16> = overall
diameter. (you multiply by 2 to get the total sidewall height, and divide by
25.4 to convert from mm to inches.)





"Phil Schuman" > wrote in message
. ..
> The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> I was wondering if the 245/70R16 sizes cause any probs
> with speedometer or front turning clearance under the cowling
> or any other considerations on going from the 75 to the 70 ?
> It seems like the overall outside tire diameter is the same, but ??
>
>
>

The width is the 225/235/245 number. The 70/75 number is the height of the
sidewall.

A 225/65, 225/70, and 225/75 are all the same width. The difference in these
tires will be the amount of sidewall, and the overall diameter -- the 65
will be the smallest and the 75 will be the tallest.

You might have noticed a loss of traction when you changed from 225s to
235s, because this would represent the width of the tire. A 225/75 and a
235/70 are within 10mm of being the same diameter.

I am a poor judge of what happens in snow, but it's difficult for me to see
where one would notice a difference in 10mm in diameter. I have to suspect
there are tread patterns and other things that enter into the discussion.



"Mike Romain" > wrote in message
...
>I will second that. We lost a 'lot' of traction when we went from a 225
> to a 235 while keeping the same profile even. Going to a wider 70
> series adds to the loss.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Bowgus wrote:
>>
>> A consideration ... if you drive in snow, and will be using the 245s they
>> may be too wide. I say this because the 235 is too wide for my XJ in snow
>> ... but the XJ is a lighter vehicle I believe (unibody). I use 225 snow
>> tires ... which unfortunately are due for replacement this coming winter
>> :-(
>>
>> "Phil Schuman" > wrote in message
>> . ..
>> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
>> > I was wondering if the 245/70R16 sizes cause any probs
>> > with speedometer or front turning clearance under the cowling
>> > or any other considerations on going from the 75 to the 70 ?
>> > It seems like the overall outside tire diameter is the same, but ??
>> >
>> >
>> >

Could be, we went from Hercules 'terra Trac' to BFG AT's and it was a
big disappointment. I believe there was over an inch of actual tread
width difference.

Mike

J Strickland wrote:
>
> The width is the 225/235/245 number. The 70/75 number is the height of the
> sidewall.
>
> A 225/65, 225/70, and 225/75 are all the same width. The difference in these
> tires will be the amount of sidewall, and the overall diameter -- the 65
> will be the smallest and the 75 will be the tallest.
>
> You might have noticed a loss of traction when you changed from 225s to
> 235s, because this would represent the width of the tire. A 225/75 and a
> 235/70 are within 10mm of being the same diameter.
>
> I am a poor judge of what happens in snow, but it's difficult for me to see
> where one would notice a difference in 10mm in diameter. I have to suspect
> there are tread patterns and other things that enter into the discussion.
>
> "Mike Romain" > wrote in message
> ...
> >I will second that. We lost a 'lot' of traction when we went from a 225
> > to a 235 while keeping the same profile even. Going to a wider 70
> > series adds to the loss.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Bowgus wrote:
> >>
> >> A consideration ... if you drive in snow, and will be using the 245s they
> >> may be too wide. I say this because the 235 is too wide for my XJ in snow
> >> ... but the XJ is a lighter vehicle I believe (unibody). I use 225 snow
> >> tires ... which unfortunately are due for replacement this coming winter
> >> :-(
> >>
> >> "Phil Schuman" > wrote in message
> >> . ..
> >> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> >> > I was wondering if the 245/70R16 sizes cause any probs
> >> > with speedometer or front turning clearance under the cowling
> >> > or any other considerations on going from the 75 to the 70 ?
> >> > It seems like the overall outside tire diameter is the same, but ??
> >> >
> >> >
> >> >

Not if the change was from 225 to 235. These numbers represent the tread
width in mm, and 10mm is the functional equivelent of 3/8".

Now, there is some misunderstanding (at least on my part) of just exactly
where they measure 225 or 235, and the actual tread blocks being square on
one tire and rounded off on the other might play a role in your perception
of an inch difference, but the actual difference is 10mm. Your point being
that you are looking at the tread patch on the ground is not lost on me ...





"Mike Romain" > wrote in message
...
> Could be, we went from Hercules 'terra Trac' to BFG AT's and it was a
> big disappointment. I believe there was over an inch of actual tread
> width difference.
>
> Mike
>
> J Strickland wrote:
>>
>> The width is the 225/235/245 number. The 70/75 number is the height of
>> the
>> sidewall.
>>
>> A 225/65, 225/70, and 225/75 are all the same width. The difference in
>> these
>> tires will be the amount of sidewall, and the overall diameter -- the 65
>> will be the smallest and the 75 will be the tallest.
>>
>> You might have noticed a loss of traction when you changed from 225s to
>> 235s, because this would represent the width of the tire. A 225/75 and a
>> 235/70 are within 10mm of being the same diameter.
>>
>> I am a poor judge of what happens in snow, but it's difficult for me to
>> see
>> where one would notice a difference in 10mm in diameter. I have to
>> suspect
>> there are tread patterns and other things that enter into the discussion.
>>
>> "Mike Romain" > wrote in message
>> ...
>> >I will second that. We lost a 'lot' of traction when we went from a 225
>> > to a 235 while keeping the same profile even. Going to a wider 70
>> > series adds to the loss.
>> >
>> > Mike
>> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> > 88 Cherokee 235 BFG AT's
>> >
>> > Bowgus wrote:
>> >>
>> >> A consideration ... if you drive in snow, and will be using the 245s
>> >> they
>> >> may be too wide. I say this because the 235 is too wide for my XJ in
>> >> snow
>> >> ... but the XJ is a lighter vehicle I believe (unibody). I use 225
>> >> snow
>> >> tires ... which unfortunately are due for replacement this coming
>> >> winter
>> >> :-(
>> >>
>> >> "Phil Schuman" > wrote in message
>> >> . ..
>> >> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
>> >> > I was wondering if the 245/70R16 sizes cause any probs
>> >> > with speedometer or front turning clearance under the cowling
>> >> > or any other considerations on going from the 75 to the 70 ?
>> >> > It seems like the overall outside tire diameter is the same, but ??
>> >> >
>> >> >
>> >> >

The 'book' width measurements are not at the tread, they are at the
sidewall.

When I went from a 31x10.5" mud to a 33x9.5" mud, the tread on the
ground went from 10.25" to 7.5". I got a 'radical' increase in
traction.

Mike

J Strickland wrote:
>
> Not if the change was from 225 to 235. These numbers represent the tread
> width in mm, and 10mm is the functional equivelent of 3/8".
>
> Now, there is some misunderstanding (at least on my part) of just exactly
> where they measure 225 or 235, and the actual tread blocks being square on
> one tire and rounded off on the other might play a role in your perception
> of an inch difference, but the actual difference is 10mm. Your point being
> that you are looking at the tread patch on the ground is not lost on me ...
>
> "Mike Romain" > wrote in message
> ...
> > Could be, we went from Hercules 'terra Trac' to BFG AT's and it was a
> > big disappointment. I believe there was over an inch of actual tread
> > width difference.
> >
> > Mike
> >
> > J Strickland wrote:
> >>
> >> The width is the 225/235/245 number. The 70/75 number is the height of
> >> the
> >> sidewall.
> >>
> >> A 225/65, 225/70, and 225/75 are all the same width. The difference in
> >> these
> >> tires will be the amount of sidewall, and the overall diameter -- the 65
> >> will be the smallest and the 75 will be the tallest.
> >>
> >> You might have noticed a loss of traction when you changed from 225s to
> >> 235s, because this would represent the width of the tire. A 225/75 and a
> >> 235/70 are within 10mm of being the same diameter.
> >>
> >> I am a poor judge of what happens in snow, but it's difficult for me to
> >> see
> >> where one would notice a difference in 10mm in diameter. I have to
> >> suspect
> >> there are tread patterns and other things that enter into the discussion.
> >>
> >> "Mike Romain" > wrote in message
> >> ...
> >> >I will second that. We lost a 'lot' of traction when we went from a 225
> >> > to a 235 while keeping the same profile even. Going to a wider 70
> >> > series adds to the loss.
> >> >
> >> > Mike
> >> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> >> > 88 Cherokee 235 BFG AT's
> >> >
> >> > Bowgus wrote:
> >> >>
> >> >> A consideration ... if you drive in snow, and will be using the 245s
> >> >> they
> >> >> may be too wide. I say this because the 235 is too wide for my XJ in
> >> >> snow
> >> >> ... but the XJ is a lighter vehicle I believe (unibody). I use 225
> >> >> snow
> >> >> tires ... which unfortunately are due for replacement this coming
> >> >> winter
> >> >> :-(
> >> >>
> >> >> "Phil Schuman" > wrote in message
> >> >> . ..
> >> >> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
> >> >> > I was wondering if the 245/70R16 sizes cause any probs
> >> >> > with speedometer or front turning clearance under the cowling
> >> >> > or any other considerations on going from the 75 to the 70 ?
> >> >> > It seems like the overall outside tire diameter is the same, but ??
> >> >> >
> >> >> >
> >> >> >

Ddi you make this change on the same rims, or did you change rims too?

There is something here that one of us is missing because there is no point
in giving a spec for tire size if that spec has no basis in reality. Why
tell the consumer the tires are 9.5 when they are really 7.5, or 225mm vs.
235mm, if they are really something else entirely?

I'm not arguing that you find the 9.50s work better than the 10.50s, I have
every reason to think you are correct in this. I don't have the same kind of
driving environment where I am, and we find around here that wider is
better, but we need to float above dry sand and dirt and the larger foot
print works better here. I'm sure that if I brought my Jeep to your house,
it would give me lots of trouble, especially in winter.

What I am suggesting is that if your tread on the ground is only 7.5 with a
9.50 tire, then there is another factor because the tread on the ground
should be closer to 9 than 7. In any case, the OP isn't getting any benefit
from this discussion.

His Grand should be fine for him with a 245/70 from the perspective of
fitment. Whether or not it provides any better performance is beyond me, but
my guess is that the actual tread pattern will play a larger role than the
tire size.





"Mike Romain" > wrote in message
...
> The 'book' width measurements are not at the tread, they are at the
> sidewall.
>
> When I went from a 31x10.5" mud to a 33x9.5" mud, the tread on the
> ground went from 10.25" to 7.5". I got a 'radical' increase in
> traction.
>
> Mike
>
> J Strickland wrote:
>>
>> Not if the change was from 225 to 235. These numbers represent the tread
>> width in mm, and 10mm is the functional equivelent of 3/8".
>>
>> Now, there is some misunderstanding (at least on my part) of just exactly
>> where they measure 225 or 235, and the actual tread blocks being square
>> on
>> one tire and rounded off on the other might play a role in your
>> perception
>> of an inch difference, but the actual difference is 10mm. Your point
>> being
>> that you are looking at the tread patch on the ground is not lost on me
>> ...
>>
>> "Mike Romain" > wrote in message
>> ...
>> > Could be, we went from Hercules 'terra Trac' to BFG AT's and it was a
>> > big disappointment. I believe there was over an inch of actual tread
>> > width difference.
>> >
>> > Mike
>> >
>> > J Strickland wrote:
>> >>
>> >> The width is the 225/235/245 number. The 70/75 number is the height of
>> >> the
>> >> sidewall.
>> >>
>> >> A 225/65, 225/70, and 225/75 are all the same width. The difference in
>> >> these
>> >> tires will be the amount of sidewall, and the overall diameter -- the
>> >> 65
>> >> will be the smallest and the 75 will be the tallest.
>> >>
>> >> You might have noticed a loss of traction when you changed from 225s
>> >> to
>> >> 235s, because this would represent the width of the tire. A 225/75 and
>> >> a
>> >> 235/70 are within 10mm of being the same diameter.
>> >>
>> >> I am a poor judge of what happens in snow, but it's difficult for me
>> >> to
>> >> see
>> >> where one would notice a difference in 10mm in diameter. I have to
>> >> suspect
>> >> there are tread patterns and other things that enter into the
>> >> discussion.
>> >>
>> >> "Mike Romain" > wrote in message
>> >> ...
>> >> >I will second that. We lost a 'lot' of traction when we went from a
>> >> >225
>> >> > to a 235 while keeping the same profile even. Going to a wider 70
>> >> > series adds to the loss.
>> >> >
>> >> > Mike
>> >> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> >> > 88 Cherokee 235 BFG AT's
>> >> >
>> >> > Bowgus wrote:
>> >> >>
>> >> >> A consideration ... if you drive in snow, and will be using the
>> >> >> 245s
>> >> >> they
>> >> >> may be too wide. I say this because the 235 is too wide for my XJ
>> >> >> in
>> >> >> snow
>> >> >> ... but the XJ is a lighter vehicle I believe (unibody). I use 225
>> >> >> snow
>> >> >> tires ... which unfortunately are due for replacement this coming
>> >> >> winter
>> >> >> :-(
>> >> >>
>> >> >> "Phil Schuman" > wrote in message
>> >> >> . ..
>> >> >> > The Grand Cherokee OE tires are the Wrangler ST with 225/75R16 -
>> >> >> > I was wondering if the 245/70R16 sizes cause any probs
>> >> >> > with speedometer or front turning clearance under the cowling
>> >> >> > or any other considerations on going from the 75 to the 70 ?
>> >> >> > It seems like the overall outside tire diameter is the same, but
>> >> >> > ??
>> >> >> >
>> >> >> >
>> >> >> >