PSI Recommendations: Yokohama S-Drive 17"

[Padawan]

Originally Posted by NukleoN

I am still looking for opinions regarding optimal tire-pressure for the OP specs. I am using 23/29 PSI but this seems really low to me.

I agree that it's quite low, and it's possible that the TMPS won't recognise 23 psi as being properly inflated regardless of whether you reset it or not. I would most likely start with the recommended pressures for the Brabus and adjust up or down slightly from there. As with the stock setup, you'll want somewhat less pressure in the fronts than the rears because of the car's weight distribution. Another "trick" you may want to try is drawing a line across the entire tread of the tires from one sidewall to the other and then driving around for a bit. By examining what portions of the line are scuffed off, you'll be able see what areas of the tire are making the most contact.

[NukleoN]

Given the 50 PSI Max, I think I am gonna do something like 30 front/34 rear or thereabouts. The scuff-line trick sounds good. Thanks for the feedback.

[sato7]

As per the smart USA Tech Training manual: 175/55/15 or 175/50/16 up front should be at 26 psi. The rear 175/55/15, 195/50/15, or 215/50/16 all should be at 32 psi.

[Old smart]

Originally Posted by NukleoN

... The scuff-line trick sounds good. ...

Chalk-lining tires was common practice in the racing game some years back, before pyrometers came into use. You have to be careful in interpreting the line though, as the results will be affected by wheel camber. The smart’s rears have permanent negative camber so the inner shoulder will show more wear than the outer, even at "proper" pressure – you might have to do it a few times (or run 2 or 3 lines across at a time) to see the picture developing. The fronts do not normally have camber, but the smart's front suspension design is such that it develops negative camber when braking hard – best to slow very gradually with as little nose dip as possible when reading those lines.

Attached is a website with good photos of chalk-line results: TheDieselStop.Com - www.thedieselstop.com

The principle is still valid for a smart.

[Old smart]

Originally Posted by NukleoN

Ok I just realized you meant 'Operaters Manual' by OpMan. I thought you were talking about some member on the forum. Never heard it abbreviated like that before. ...

Sorry 'bout that - a previous life of mine was a flurry of OpOrds, OpPlans, FragOrds, OPTEMPOs, OPSEC, etc.