ceboyd

o.k. with all the treads about harsh rides.. I was wondering if anyone ventured to downgrade to 17" wheels so that a 50 profile tire would be used making the tire a bit cushier..

..yesterday I placed a 17" Infinit Q45 wheel and tire on the front and back and found out that it clears the brakes without any problem... BUT although the offset and bolt pattern is correct, the hub center is NOT... so the Infiniti wheel could not be used..

...but I am wondering if the 17" could be used? This could potentially alleviate a lot of frustrated people with the harsh ride quality..

I realize many are upgrading to 19 and 20 inch wheels instead but I thought I'd ask to see if anyone else has done this yet and if yes, what type of wheel and tire size they used.

Manaray

hmmm, don't think too many people would go BACKWARDS like that...do you have run flats? Those tires suck in terms of ride quality. Just change your tires to some normal ones and the ride should improve...

joeyb

I haven't done it, but I'm also considering it. So, if anyone has, I'd also be interest in their experience. I'm also interested in people's experience in mounting the pressure sensors in aftermarket wheels.

I was thinking of 17 x 8 wheels and 245/45/17 tires. This gets the same tire size as stock. It's also the same tire as the front of a Corvette, which means there are a lot of tires available.

pot_head

i currently have aftermarket 18" wheels. they are cheap wheels tho. but the local tire/wheel shop just took off the sensor and mounted it on the new wheels with ease keeping the stock runflat tires. and keep in mind, i was watching them do it and these ppl who mount tires and stuff arent any professionals by far.just a couple highschool kids that work there. and the tire pressure warning light on the dash doesnt come on at all.

jcmartz

I may be able to offer some actual data on this subject. Last year, just before the expiration of the lease on my 98 GS400, I also purchased a 97 SC400. The GS400 had 17" wheels while the SC400 had the stock 16" rims. As it turns out, both cars had the same tire - Yoko AVS Intermediates (I had purchased these for the GS400; they came on the SC400). Anyway, the ride on the GS400 had always been rather harsh, similiar to some of the observations you see on the SC430. (so harsh, this car, too, had been in for service and several procedures to correct steering vibration). The vibration on the GS was never completely removed. Contrary to this, the ride on the SC400 was wonderful. Not too soft, but none of the skittishness of the GS400.

So, I switched the tires/rims between the 2 cars: amazingly, the ride quality also switched with them. The GS400 went from harsh and skittish to smooth and controlled. More amazingly, the vibration in the steering was all but eliminated (there is a long story about the steering vibration in the early GS400s; it wasn't a tire balance problem). Just as interesting, the SC400 degraded remarkably: the car now tracked the little lines in the pavement, etc. This exercise was so eye-opening, I was shocked that more controlled tests like this haven't been reported (especially in the main-line car mags).

So, I would seriously consider moving to a smaller rim on my SC430 except that my car is leased. I'll switch out the run-flats when they wear out, but othwerwise, I'm confident a reduction in rim size would markedly help the ride on the SC430. Please note that the SC430 is built on the same platform as the GS430, and hence, I think the results above are perhaps more applicable to our cars than you may think at first glance.

Your mileage may vary,

Joe Martz

ceboyd

I figured it would be a much improved ride with 17s

NREIFF

CEboyd-

I know this a an old thread but I just saw it and was wondering if you ever did anything with the wheel size.

I have been thinking about for over a year AND I have the non-runflat tires.

I have blown through 3 tires and have had five wheel repairs!!

Let me know if you have done anything with the rim downsize.