Front Tyre Wear

[Wallace]

Well i had two TOYO TR 1's put on the front yesterday, and wow what a difference! No more "tram lining" no more veering into the kerb. Unbelievably smooth, bit more harsh on some bits of road, but didn't realise how bad the Bridgestones were. The garage put in 33psi as they said it wasnt worth ruining a luxury car with the harder ride that 36psi would bring. I've put them on 35 to see how it goes.

[folver]

Firstly, sorry for digging up this oldish topic. I am a new member and I browsed this forum a lot (found a lot of helpful information) when I was planning to order the car in 2006.

Just recently I noticed that both outer sides of the front tires are substantially worn. I thought it was down to overly high cornering speeds. But the other day I found one of the front tires flat while the car was sitting in the parking lot. Turns out, the inner sides of the tires were worn even more badly, so on of them had torn and didn't keep any air in it. This was surprising especially as the centres, where the wear indicators are, still had 3-4 mm of tread left. I have always kept the tires inflated to the recommended specs, so I will outrule underinflation.

The workers at the tire shop said it was nothing new to them, and they had had several Lexus, BMW and Mercedes owners with the same problem. Just my theory, but can it be that when you turn the steering wheel all the way to the left/right, the front wheels tilt a bit to help decrease the turning circle, and such a wide and low profile tire doesn't flex enough and simply wears out the sides it's on? (Most RWD luxury cars should do this tilting thing, right?) Oh yeah, I have the 17" 225/45 fronts; 245/45 rears. If this theory was indeed the case, the 18s would wear even faster, wouldn't they?

Seeing as the center part still had plenty of tread left and the rears have worn perfectly evenly and still offer plenty of grip even after 55 000 km (and 2,5 years), I was just a bit shocked to be throwing away what at first looked like perfectly usable tires.

2.4 bar front and 2.6 bar rear is already a high enough number on the border of stiff. After this I have tried increasing the pressures in the fronts to 2.6, but they became a bit too bumpy and lost too much grip as well. Considering the roads I have to travel daily, that isn't really an option. Furthermore, I rarely ever exceed the 160 km/h speed that Lexus has recommended an increased tire pressure for.

I am not saying that getting so many kilometres out of the original tires (Dunlop SP Sport Maxx, which were amazing both on tarmac and surprisingly gravel) is not great, but still it makes you wonder if there is anything to be done to avoid wasting tires like this in the future. (adjustments to the undercarriage or whatever)

I am no engineer or mechanic, but still I hope to receive some helpful comments while avoiding hateful ones.

[Roger Bill]

Hi Folver

A few thoughts which might help:

Here in the UK tyre wear on the inner edges has become a much bigger problem in recent years because we now have a lot more speed cushions. These only extend across part of the carriageway width and are designed to allow larger vehicles to straddle them without slowing down. However, when a car straddles them the inner tyre edges are subject to significantly increased strain, especially as the outer edges of speed cushions are often damaged. Damage to the inner edges of tyres often goes unnoticed and can be very dangerous. This plus the environmental disadvantages associated with shortened tyre life and increased fuel consumption are, in my view, good reasons why most speed cushions should be replaced by alternative speed reduction measures.

Steering misalignment is another common cause of uneven tyre wear. Also, especially given the relatively small turning circle of the IS250, travelling at anything more than a few mph with the steering on full lock would cause the tyres to scrub and wear quickly.

The Lexus recommended tyre pressures for the IS250 seem rather high. I’ve only had my IS250 for 3 months and so far have been using the recommended pressures. A few weeks ago I suffered a small back injury and so I’m intending experimenting with slightly lower pressures in the hope of achieving a slightly softer ride. If my back troubles don’t improve I might even consider switching from 17” to 16” wheels if these and the higher wall 205/55 tyres give a softer ride.