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DPBest

Downsizing 18" To 17" Rims - Question

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I have a 2007 IS350 with 18" rims, live and drive in a city with rough roads and the ride quality is rattling me to bits. I'm considering dropping down to 17" rims to get a taller and more (hopefully) supple tire. I'm willing to give up cornering performance for ride quality. How much of a difference would I notice by changing the wheels to 17" versus current 18" (excluding any differences in swapping out the tires to a different brand/model)? On the same topic, which tires would you recommend for the 17" rims assuming my goal is ride quality and low noise? Thanks

DBest

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Rough roads in San Francisco? Your streets and highways seem wonderful compared to some of our cratered streets in the Kansas City area. Even the 100 mile pavement/gravel stretch of Highway 1 between Monterey and Cambria I drove in February was smooth by comparison ... or maybe it was the scenery that make them seem good. Ah, yes ... I was wearing shirt sleeves in Golden Gate Park while it was snowing back in Kansas.

I think you would notice a substantial improvement in comfort by switching to 17" tires and keeping them near the minimum recommended tire pressure. If you are looking for maximum comfort, you could even go with the standard IS250 setup of 225/45-17 tires front and rear instead of the standard IS350 setup of 225/45-17 front and 245/45-17 rear.

You might get a little undesired rear wheel spin with 225/45-17 tires on the back but your traction and stability controls should manage it unless you drive like an idiot. And you should get cheaper tire prices by avoiding 245/45-17 on the back. The IS350 is a powerful car but my 2000 LS400 does just fine on its standard 225/60-16 tires and it has power (-16 hp) and torque (+23 lb-ft) ratings similar to your car and a curb weight higher than an IS350 only by an amount equal to the weight of my beer swilling Concord CA brother-in-law.

A good place to start is to compare the comfort ratings in the surveys at http://www.tirerack.com although you may see ratings only for the tires they have in stock.

I suspect you could do a swap with, plus get some cash from, an IS250 owner who thinks your bigger wheels and tires are "cool".

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When changing to 17" rims, you should experience a positive step-up in comfort, as there's obvious more sidewall to dampen out vibrations and shocks. Considering the road conditions you mentioned, I wonder if this will be satisfying enough. It's always some sort of trade-off between comfort and sportivity/handling charasteristics. Perhaps you get the best results with a 16" rim.

From personal experience, I would recommend the michelin primacy mxv4 all-season tire. Best thing you can do is speak to your tire-center and do some lookups on performance tires, as charasteristics may vary on climate.

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From personal experience, I would recommend the michelin primacy mxv4 all-season tire. Best thing you can do is speak to your tire-center and do some lookups on performance tires, as charasteristics may vary on climate.

I like the Michelin Primacy MXV4 set I bought for LS earlier this year but unfortunately it not available in either size 225/45-17 or 245/45-17 that would be needed to do a IS250 or IS350 standard wheel/tire size configuration. Whether or not 16" wheels would clear the brakes is an interesting question but that would mean using aftermarket wheels or wheels from a different and probably older Toyota or Lexus model.

The main problem I've found with aftermarket wheels is trying to find a replacement if one gets severely damaged. I sure wish I had bought OEM Lexus wheels to use with my snow tires back in 2003 instead of aftermarket wheels ... won't make that mistake again.

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Thanks very much for the comments. If San Francisco weren't tearing up the streets all the time to (pick one) replace sewer line, replace water mains, burying electrical supply lines, putting in new trolly tracks, add wheelchair friendly curbs, etc. the roads might actually be fine. But there are always a ton of steel plates covering some big work hole all the time and they don't do anything to ease the transition from pavement to steel sheet 1 inch higher.

I know 16" rims won't fit with the 350's brakes - already explored that. As for swapping a 250 rims with my 350, I don't think the other party would be all that interested in my chewed up rims (parallel parking rash). So I'm left with aftermarket rim choice (since Lexus wants $2400 for a set of 17" OEM rims). A guy at Tirerack is recommending the following - and I see what you mean about the wider rear tire prices:

Front Tires 225/45r17 Michelin Primacy MXM4 91H $150 each

Rear Tires 245/45r17 Michelin Primacy MXM4 99H $244 each

http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Primacy+MXM4

I'm not sure what the difference is between the MXV4 and MXM4.

Wheels 17x8 OZ Ultraleggera Bright Silver Finish $263 each

http://www.tirerack.com/wheels/WheelCloseUpServlet?target=wheelCloseUp&wheelMake=O.Z.&wheelModel=Ultraleggera&wheelFinish=Bright+Silver+Paint

They also carry a more conventional OEM-looking rim that's cast in China, and of unknown quality - but they're half the cost of the OZ's. FUD is gripping me hard on that tradeoff.

DBest

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Fine with comfort but why buy a luxury sports sedan like an IS250 if your going to downsize on performance and handling and style for comfort. Should have bought a ford ranger!

Good luck with your new wheels.

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Fine with comfort but why buy a luxury sports sedan like an IS250 if your going to downsize on performance and handling and style for comfort. Should have bought a ford ranger!

Good luck with your new wheels.

Actually, the OP has an IS350 (not an IS250) with the optional 18" wheel and tire package. Based on his post of many months ago, he was only considering installing the same wheel and tire size that was standard on the 2007 IS350. He wasn't considering anything radical.

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Fine with comfort but why buy a luxury sports sedan like an IS250 if your going to downsize on performance and handling and style for comfort. Should have bought a ford ranger!

Good luck with your new wheels.

I disagree with you. I think there is a sweet spot between performance and comfort, and I think Lexus dropped the ball with the 18 inch package on the IS350. Most people who own an IS350 didn't buy it to race or drive aggressively all the time, I think you'll find that most IS350 owners bought it because they love to have the power when they need it, such as when passing a car or merging onto the freeway. :)

To the OP: I have my IS350 in for service right now. They gave me a 2011 IS250 for a loaner that still has the same 18 inch rims and tire size as my 350, but instead of Z rated, they put Y rated, Dunlop SP Sport 2050... The ride quality is awesome compared to my 350.... Although Lexus may have added more noise dampening and suspension improvements in the 2011 model. :)

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