Tire Pressure with 175/70 13 ?

[Bluefield]

Greetings,
When looking at the 175/70 R13 tires on my S1 they look like they need a little more pressure. As I am a recent owner I thought it best to ask what you are using. Right now I have around 1,6 bars in all four tires. What would you recommend?

Thank you,

Bluefield
26-3811

[GrUmPyBoDgEr]

An odd Tyre size for an Elan.
I think your pressures are too low & the best way is to pump them up until you feel happy with the way the Car handles, weighed up against what you expect regarding comfort.
This question was discussed not to long ago, check it out in the Archives.
Basically it boils down to Tyre size, make & individual preference.
I run pretty high pressure because I like the lightness of steering & the prompt "turn in" response with the Continental 175/60x14 Tyres on my S4 Elan.

Cheers
John

[bcmc33]

I did a lot of playing with tyre pressures last year and ended up with the best being the standard 18psi fronts and 23psi rears.
All the informed people in the club said the standard will be the best - but I knew better

[Galwaylotus]

I did a lot of playing with tyre pressures last year and ended up with the best being the standard 18psi fronts and 23psi rears.
All the informed people in the club said the standard will be the best - but I knew better

Tell us more please, Brian. What makes that setup "best"? Is it comfort, grip, turn-in? Inquiring minds want to know!!

[msd1107]

Tire pressure is also influenced by wheel rim width.

The standard 4.5" rim is adequate for 145 section width tyres, is marginal for 155 tyres. The +2, using 165 tyres, went to 5.5" rims. So going to 165, 175/70, 185/70, 185/60 tyres should get an upgrade in rim width.

Narrow rims need less pressure to get even tread wear. This has the side effect of lower cornering speed, longer stopping distances, increased fuel consumption, etc although the ride will be more compliant.

A wider rim can use higher inflation pressure and that increases cornering speed, stopping distance is reduced, steering feel and precision is enhanced, etc.

On my standard 4.5" rims and 155 tyres, I found cornering improved with 23/28 pressure compared to the 18/23 that is recommended for low speed driving. When I went to 165, and then 185/70 tyres, I upgraded to 5.5" rims and 28/33 pressure. This combination produced the most precise steering and best cornering.

In theory, a 175 or 185 tyre could use a 6" rim, but there are enough clearance issues at the rear without the wider rim making them worse.

So if you remain with the stock 4.5" rims, you will need lower tyre pressures to get even tread wear, or live with uneven tread wear (as if you will wear out the tyres in normal driving) when using higher inflation pressures for optimum performance.

David
1968 36/7988

[summerinmaine]

An odd Tyre size for an Elan.
I think your pressures are too low & the best way is to pump them up until you feel happy with the way the Car handles, weighed up against what you expect regarding comfort.
This question was discussed not to long ago, check it out in the Archives.
Basically it boils down to Tyre size, make & individual preference.
I run pretty high pressure because I like the lightness of steering & the prompt "turn in" response with the Continental 175/60x14 Tyres on my S4 Elan.

Cheers
John

The size may be odd, but I found very limited choices for the 13" wheels. Particularly if I wanted "performance" tires. So I opted for 175/70X13 as well. I'll watch this thread with interest, and do some playing after I settle my other suspension/ride height issues.

[GrUmPyBoDgEr]

I did forget to mention the Wheel size on my S4 which is 14" x 6J, using those 175/60 x14" Tyres.
I've noticed that some have managed to "shoehorn" 185/60's on identical Rims on to an S4.
With earlier cars the Wheel Arches will not permit this combination without major modifications.
Yes with the 14" Wheels & 175/60's the choice of Tyres is also very limited i.e. No Yoko's at all.
Regarding suitable Tyre pressures, the important parameter is not how the Tyre looks but how it behaves & your personal style of driving.
Each of us will have our own preferences.

Cheers
John

P.S. some time ago I raised the subject of Tyre pressures, which in the past seemed to have been overlooked as a vital Factor amongst the continuing "Tyre choice" debates.
Different Tyre pressures will transform an Elan's Handling / Performance / Road Holding

[msd1107]

175/70-13 is not a particularly odd size, but is the natural 70 series upgrade size for 155-13 tyres.

For instance, 155-13 has 912 rev/mile. 175/70-13 has 917 rev/mile. The appropriate 60 series upgrade would be 205/60-13 which has 916 rev/mile. These are all the same rolling diameter within less than 1%.

+2s stock size is 165-13 with 887 rev/mile. Upgrades are 185/70-13 with 893 rev/mile and 215/60-13 with 897 rev/mile.

The commonly fitted 185/60-13 has 956 rev/mile which is much too small. You would need 185/60-14 with 915 rev/mile, 195/60-14 with 896 rev/mile, 185/55-15 with 904 rev/mile or 195/55-15 with 887 rev/mile.

http://bit.ly/b5xI64 has a down loadable spreadsheet that allows the user to explore all these details in whatever detail they want.

David
1968 36/7988

[bcmc33]

Wierd things happening today - two PMs sent were delivered to me and not to the persons I addressed them to and the reply I made to Galwaylotus has been deleted.

I can't be bothered to rewrite up the complete reply - so here's the pr?cis:

175/65 R14 x 5.5" Minilite wheels. (maintains the original 13" rolling radius).

The tyres were first set at 23psi (F) & 28psi (R) as this used to be the sprint/hillclimb pressures used on a previous S2 lifetime.

These pressures were found to be very skittish (my word for it) when driven hard on fast bends, far too sensitive with a definite feeling of oversteer. Fine for normal driving.
Many combinations progressively lowering from the 23/28 set-up plus a number of same pressure all round in pursuit getting the right confident feel for grip and turn-in.
I was really pissed when the standard settings proved to be the best.

[reb53]

"I was really pissed when the standard settings proved to be the best."

I s'pose there is the theoretical possibility that the original pressures had Jim Clark's blessing......wouldn't be pissed off then would you!

Ralph.

[Galwaylotus]

Thanks, Brian. A different setup to the original then. My car has 155-13 on the front 4.5 inch standard rims and 175-13 on +2 5.5 inch rears (26R rear wings). I felt it a bit mushy with the original factory settings. I haven't reall played around with the pressures yet so I was interested in your findings and reasons.

[ftsoft]

I am now and always have run 32 psi all around (43 years) . The car is almost perfectly balanced, so I don't know why you would run different pressures. My S2 does not handle well with 18 psi. I ran 40 psi for Autocross and scca cp.

Frank

[ftsoft]

Oh! and how is the clearance with the 175/70's ? I've always had some clearance issues with 155/80's.

Frank

[GrUmPyBoDgEr]

Seems like we're running this Topic "through the Mill" once more & not too long after there was a fairly lengthy similar thread on here.
Tyre choice question regularly crops up frequently where one consideration is correcting the Speedo to the Tyre Size & rolling Radius; a purely Mathematical problem at which David is so good.
IMHO the rest is up to the Individual.
We can all start off with the "Owners Manual recommendation" & play tunes on that until each of us attains the Elan that he/she enjoys driving
e.g:-
My Elan has a Zetec Engine which I like. Not everybody does!
" " " a Spyder Space Frame which I like. Not everybody does!
" " " a non Standard Paint colour which I like. Not everybody does!
" " " Wider low profile Tyres which I like. Not everybody does!

The old saying "One Man's Meat is the other Man's Poison", could be applied, maybe?

Maybe there could be Insurance/Legal implications running Tyre pressures other than those stated in "the Manual"?
But I'm not worried; I run the pressures that I feel happy with

Cheers
John

[khamai]

175/70-13 tires can be squeezed onto a 4.5" wheel, but 5.0 or 5.5 would be better. Some flaring would be needed at both front & rear.

As for pressures, I would start with around 26 psi for all four and possible go as low as 22 or 23 psi. I suggest starting at say 28 psi and chalking the shoulders of the tires and get on a skid pad (round-a-bout?) and see how much the tire is rolling over. Continue lowering the pressure in 2 lb increments until you see the tires rolling over. Then bump the pressure back up in 1 psi increments until you see the correct amount of roll over.

Cheers,
Kiyoshi