I just bought a certified '06 GS430.

It has 225/50R17 tires on it.

The Manual and door sticker specify 245/40R18 tires.

The overall diameter of each is within .15" so the speedo and skid systems
shouldn't know the difference.

I think the 225/50R17 would provide a smoother ride because the sidewalls would provide about a half-inch more 'cushion'.

I'd really like to have the called-for 245/40R18's because I feel the skid systems were engineered for that tire's footprint, etc...and because Lexus SPECIFIED those tires for, presumeably, a good reason.
The dealer is balking at putting the correct tires on it.

Is there anything I'm missing here?

Thanks,
WhitBaby

 

the 430s in the US all came with 18s, someone swapped for the rims before getting rid of the car, as far as arguing about the skid systems, i think that is going to be hard to sell. If you bought it already I think its your baby....what is on there, 10 spoke design ???

 

Yup, 10 spoke wheels.
They're in good shape. I suspect the previous owner had a friend with a GS300 and just traded with him before trading in the 430, or I suppose the dealer put them on for a smoother ride.

I wasn't looking for advice on my options, I was looking to see if there were any SIGNIFICANT advantages to one size over the other.

The 17's are:
Cheaper to replace.
Smoother ride.


The only advantage to the 18's would seem to be the 3/4" wider contact patch. Plus it seems they would hydroplane easier than the 17's.

 

OMG, you got robbed!!!

You should go back to the dealership and demand for the proper set of wheels/tires. Especially when you purchased the "Lexus certified," everything should be the OEM equipped including the wheels/tires!!!

But be sure to get the Michelin Primacy HP or PS2 instead of Yokohama Advan A10B!!!

 

there should be little effect on vdim vsc etc. i think the 18s look about 18 times as nice but hey its your ride, you like them, you should be OK for sure, as those 17s are put on the gs350 as the base wheel still