speedemn

I have searched a few threads on the forum and have not seen this discussed... and I am getting conflicting advice from different reputable tire shops in the area so I am hoping that I can get some advice here.

My 2008 RX 400h 4WD (recent purchase) has the stock 235/55/18 tires on the stock Lexus hybrid rims. I imagine that this is in fact the stock size for this vehicle?

When shopping for snow tires I believe that the consistent recommendation is to step down -1 to 17". One shop is recommending 235/60/17 and another shop is recommending 225/65/17 citing that the other size would cause issues with the 4WD system.

Can I get advice and recommendation on this please?

Thank you.

RX330inFL

The base tire size for your RX400h was 225/65-17. The plus 1 size upgrade provided by Lexus was 235/55-18. Those are the sizes you should consider.

Am going to guess the one shop tried to sell you the 235/60/17 because that was what they had and/or could make more money on the deal. However, if you had purchased four tires, one for each corner, you would not have had any problems with your AWD system. Only a problem when you mix and match sizes.

If you want to get snow tires for your existing RX wheels you will be fine in just having the shop swap out your current tires for an appropriate set of 235/55-18 snow tires. Your costs will be just for the tires and balancing each winter and spring as the other set goes back on your vehicle.

The other solution would be to purchase another set wheels. You can go with either 17" or 18". Just make sure they are the appropriate bolt pattern and offset to fit your vehicle. Think about purchasing an additional set of TPMS sensors for the new wheels. You will need to have these programmed to be recognized by your vehicle. Once balanced you would just need to swap the wheels each season.

For additional information, I might recommend you have a look at Tire Rack and use the tools there to see what wheels and tires are appropriate for your RX400h. Feel free to come back here and ask questions as needed.

speedemn

This is great info, thank you. I did end up going with 225/65/17 as narrower would be better for winter snow driving and going -1 would save some $ on snow tire purchases.

I will keep the stock 18" summer rims for summer tires.

Thank you for the tip on TPMS... definitely will have to address this.

rcy

I know it's too late as you've already bought your tires, but I ran 235/60/17 on my 400h for two winters with no problems.

If you check here using this handy tire size calculator

http://www.miata.net/garage/tirecalc.html

you'll see the diameter on factory 18" is 28.2" and diameter on 235/60/17 is 28.1

Compare this with 225/65/17 where the diameter is 28.5".

The goal when + or - sizing a tire is to keep the diameter as close as possible to the original tire.

So you can't go wrong with either size, but 235/60/17 will be closer to the diameter of the factory 235/55/18.

I know everyone says thinner is better for winter, but does anyone out there really think 10 MILLIMETRES (the difference between P235 and P225) is going to make a difference? Now, if you're comparing P155 width to P235 width...yes...that's going to make a difference.