I understood, rightly or wrongly, that for an Mk1 MX5 the tyre pressures were 26 psi. My Mk1 has 195/50R15 tyres - the alloys probably came off a Mk2 sometime long long ago - and I was told today that 26 psi was too low, it should be 30psi. The comment continued that at 26 psi the alloy wheels could be getting buckled because the tyre was too soft at 26psi, especially in view of the “Pot Holes R’Us” roads we have today, hence the need for 30psi.
What does the team think on this? Anyone got any comments on this? What pressure do other people use on their Mk1’s? Is 30psi the way to go?
Many thanks to all who have replied - 26psi seems to be the universal opinion so far!
Interesting comment about 30psi from Geoff, that at 30psi his car jumped about all over the road. I had thought that 26psi might also reflect the relatively low weight of the car, and that at 30psi the car’s weight might not place enough load on the wheels, hence the bouncing - seems is if that was what was happening with Geoff.
I think 26psi, which has served me well enough up to now, is OK and just to try and avoid the potholes as far as is possible, which is what we try and do anyway if we can, cars coming the other way or in the lane beside permitting, and also if we can see them early enough, not always as easy as one would think.
Hi Rod, interesting you run on 28psi - how do you find the car, OK I guess otherwise you would run a different pressure.
When I first got my MX5 I sent it into the very good local garage for a check over, the bossman did it and found the tyre pressures all over the place - 15 to 43psi ! - so put 28 in all round.
Do you run 28psi because you have 15"wheels instead of the standard 14"? It has made me wonder.
Hi Chris, within a quite reasonable range what ever tyre pressure suits your driving is fine.
Lower pressures will give a more comfortable ride, but equally use more fuel, higher pressures will generally sharpen the car up and support the car more in corners. Like everything there is a “happy” region to work in.
The rubber in the sidewall flexes and internal friction creates heat in this and so the principal of more pressure reduces this. You will see on most cars these days a sticker on the door or somewhere giving a “normal” pressure and one for load and speed.
Beyond this again, the principal of more air will reduce flex in the sidwall or effectively stiffen the whole tyre meaning the tread is forced to move more and gets warmer. (If you filled the tyre with concrete the only bit that could move would be the tread ni contact with the road.)
26psi is what the hand book will state, however I have also read on this very forum people so obsessed with this pressure that the world would end if not observed. The average gauge is not that accurate, you have to spend a great deal more than £15 at Halfords for that, and pressures alter with temperature. Park your car in the sun and the sunny side can well read 5psi more than the cold side and so on and so forth. In addition nearly, if not all tyres that the car originally came on (You can still get the Yoko A460 at a price) will have been long replaced with new designs. Any advice in MK1 manuals has to be considered to be at least 20 years old.
People will generally put more pressure in because, depending on tyres, the car can feel floppy at this if you corner enthusiastically. You can also to some extent tune the handling with pressure variations. What I would say is be cautious with any pressures below 22psi. At 20 and certainly 18psi you should be very obviously be able to see the tyre looks low.
I know I spend a lot of time looking at tyres, but it does amaze me to read that some tyres are checked by garages and found to be at 12psi or less. Not only should that be able to be felt in driving easily but the tyre would look so obviously flat.
