RE001 review

TieNN89 · Postby **TieNN89** » Sun Jul 13, 2008 1:16 am

drifter wrote:Same size 16" T1R is 8.6kg

Is that Toyo Proxes T1R?

I just made a post up for tyre weights

http://www.mx5cartalk.com/viewtopic.php?p=411595

TieNN89 · Postby **TieNN89** » Sun Aug 17, 2008 4:13 pm

What psi is everyone using the re001 on? 195/50 R15

marcusus · Postby **marcusus** » Sun Aug 17, 2008 4:29 pm

I'm running 34psi, but I think it's too much. I was getting pretty average (and when I say average, I mean below average) fuel economy with the Adrenalins, so I think when I put them back on the car I'll drop them to maybe 30 and work my way back up til I find the sweet spot for economy.

rjastra2 · Postby **rjastra2** » Mon Aug 18, 2008 11:22 am

marcusus wrote:I'm running 34psi, but I think it's too much. I was getting pretty average (and when I say average, I mean below average) fuel economy with the Adrenalins, so I think when I put them back on the car I'll drop them to maybe 30 and work my way back up til I find the sweet spot for economy.

Why would reducing tyre pressure improve fuel economy?

marcusus · Postby **marcusus** » Mon Aug 18, 2008 8:43 pm

rjastra2 wrote:Why would reducing tyre pressure improve fuel economy?

Because it depends on the make/model of the tyre. Correct me if I'm wrong, but I'd say each make/model of tyre would have its own pressure sweet spot for maximum fuel economy.

If you had your current tyres up to 40 psi, do you think your economy would be worse or better? What if it was down at 20 psi?

bigdog · Postby **bigdog** » Mon Aug 18, 2008 9:29 pm

More pressure = smaller contact patch = less friction = better fuel economy. Obviously you will eventually reach a point where 'she canna take any more cap'n' and the whole thing will explode, but the but until then the theory applies, as does the converse - less pressure = worse fuel economy. Interestingly there is a 'sweet spot' as you call it, but this relates to braking and cornering particularly, not economy. The sweet spot for braking is generally where the maximum contact patch is available - as this means the tyre is able to maintain grip and apply the force generated by the brakes most efficiently. For cornering its a whole lot more complicated and beyond my meager skills to explain here - there are some great text books on the subject though

marcusus · Postby **marcusus** » Mon Aug 18, 2008 9:59 pm

bigdog wrote:More pressure = smaller contact patch = less friction = better fuel economy. Obviously you will eventually reach a point where 'she canna take any more cap'n' and the whole thing will explode, but the but until then the theory applies, as does the converse - less pressure = worse fuel economy.

I would hazard a guess and say that economy would peak at some amount of pressure then drop off a la bell curve style. I very much doubt that it will plateu once it's reached any pressures greater than a certain amount, which seems to be what you're implying here.

bigdog · Postby **bigdog** » Mon Aug 18, 2008 10:38 pm

It would peak when the contact patch (friction) is at its smallest, and no doubt that would occur some time before the tyre explodes - the side walls would start to bulge for example. When entering an economy run (popular events in the 70's) it was common practice to inflate the tyres to 45 or 50 psi to enhance fuel economy. More pressure may have helped, but the risk of blowing the tyre out on bumps/potholes etc became greater. I doubt there would be a drop off effect, as it purely relates to friction - and friction would simply plateau, not decrease. But hey, I'm no physicist, and short of setting up a controlled experiment I doubt we will ever know...

marcusus · Postby **marcusus** » Mon Aug 18, 2008 11:08 pm

bigdog wrote:It would peak when the contact patch (friction) is at its smallest, and no doubt that would occur some time before the tyre explodes - the side walls would start to bulge for example. When entering an economy run (popular events in the 70's) it was common practice to inflate the tyres to 45 or 50 psi to enhance fuel economy. More pressure may have helped, but the risk of blowing the tyre out on bumps/potholes etc became greater. I doubt there would be a drop off effect, as it purely relates to friction - and friction would simply plateau, not decrease. But hey, I'm no physicist, and short of setting up a controlled experiment I doubt we will ever know...

I don't dispute that as you increase tyre pressure you reduce your contact patch. However, there surely would be a point where the lack of adhesion would create a negative effect since less of the power being generated by the engine is actually getting to the road via the tyres? Less contact = less grip = more radial changes with less lateral change?

As for a controlled experiment, the best I've done is played with my tyre pressures a month at a time with no change in driving style (as best as you can do anyway). I should really analyse the data properly and see whether I can find a correlation between higher pressure and better economy, but I seem to recall that having the pressure higher than a certain point made it worse.

Alex · Postby **Alex** » Mon Aug 18, 2008 11:22 pm

but once you go so far with the pressures you will have trouble with even tyre wear

rjastra2 · Postby **rjastra2** » Mon Aug 18, 2008 11:38 pm

marcusus wrote:
rjastra2 wrote:Why would reducing tyre pressure improve fuel economy?

Because it depends on the make/model of the tyre. Correct me if I'm wrong, but I'd say each make/model of tyre would have its own pressure sweet spot for maximum fuel economy.

If you had your current tyres up to 40 psi, do you think your economy would be worse or better? What if it was down at 20 psi?

The PoGo runs 38/35. I can guarantee the economy would get worse under that pressure.
I would expect the economy would improve if I raised the pressures to 40psi and above.

It was the reason the VE commodore got an unexpected raise in recommended tyre pressures prior to release. To get a reduction in the placarded fuel economy figures.

Hot Rodders · Postby **Hot Rodders** » Tue Aug 19, 2008 9:52 am

marcusus wrote:I'm running 34psi, but I think it's too much. I was getting pretty average (and when I say average, I mean below average) fuel economy with the Adrenalins, so I think when I put them back on the car I'll drop them to maybe 30 and work my way back up til I find the sweet spot for economy.

32 PSI works for me. Good economy and grip in both wet and dry. Wear on tyres is even.

manga_blue · Postby **manga_blue** » Tue Aug 19, 2008 3:27 pm

I've tried mine from 26 up to 38 psi. 28 all round was best for grip, ride and noise and equal to anything higher for turn-in. I'd say these tyres really like to run soft.

bensale · Postby **bensale** » Tue Aug 19, 2008 7:27 pm

Alex wrote:but once you go so far with the pressures you will have trouble with even tyre wear

You are more likely to increase wear due to a lack of pressure. I believe that anything up to 48psi on most tyres is safe and wont result in increased wear in the centre of the tyre.

I have my turanza's @ 40psi at the moment, it feels a touch too high. I found 38psi front 36 rear to felt the best. And I am wearing the shoulders slightly more than the centres, but I think this is due to the alignment specs.

Caffeine · Postby **Caffeine** » Thu Aug 21, 2008 2:17 pm

Close to 10000km on these tyres now, they feel great!

Lots of grip, and when they do let get, it's very smooth and predictable, more so than any other tyre I've every dríven on

Wet grip is great too.

I have a nail in the right rear, but it's not losing pressure so I'll keep an eye on it and get it fixed if it causes any problems.