Hello Team!

I recently joined the team with a 2015 Lexus GS 350 AWD 2 months ago. I'm currently having issues with traction on the rear wheels which is odd. I'm planning on purchasing a tire set for the rear. Right now the car sits on 235/45/18 front and 235/45/18 rear. I want to go a bit larger in the rear , something similar 255//45/18 rear and keep the front 235/45/18 so I won't have to worry about rubbing. Is this the correct approach? I'm also purchasing Tanabe NF210 springs for a minor low. 15mm spacers in the front and 20mm spacers for the rear. Also, since it's AWD would I need to put all 4 sets on at the same time as well or can I install 2 rears and work my way to the front. What are everyone's thoughts?

 

A oof of folks - myself included in a few months - upgrade to 245/40/19. The speedo error is negligible (less than 1% I believe) and it allows you to pick from a variety of great tires in that size. Also, the very subtle increase in size helps mitigate the wheel gap on the AWD models too.

 

As far as replacements schedule, yes, with an AWD car you are supposed to replace the tires in sets of 4 as an even wear/patterns can screw with the handling or AWD functions. I had a leak in my tire last week but, luckily, since they were replaced when I bought the car less than 1000 miles ago, I was able to just replace the one tire with the leak instead of all 4. I'll be switching to the new Michelin Pilot Sport 4 all-season this Spring in 245/40/19.

 

https://www.tacomaworld.com/tirecalc...5r18-255-45r18

The 255s will be 2.7% bigger than the 235s when new. When combined w your worn front 235s, that difference will be even greater.

GS AWDs are always sold w all four wheels the same, and it is recommended that tires have similar wear and thus circumference. I cannot find any specific guidance on just how much variance front to back is acceptable.

 

I'm being too lazy to do the research and math myself, but look up the AWD IS. It comes from the factory with a staggered setup. If you keep the percentage difference in rolling diameter within what they do on the IS, which has the same AWD system, you should be fine.

 

@JDR76 Good info.

Here's the comparison: https://www.tacomaworld.com/tirecalc...0r18-255-35r18

Circumference difference is .2%. 225/40R18s are almost identical circumference to 255/35R18s.

I think it's safe to say that OP's proposed solution well exceeds any recommended variance as might be caused by unequal wear, which is already discouraged.

 

Thanks for not being lazy like me.

I agree with your input.

 

Welcome to the club! A 245/45 series tire on all four wheels is the way to go on your AWD GS @MarxonCap

 

I checked out the tacoma link it's great information(bookmarked).
I'm considering going 245/45/18 front & rear like most recommend. Would you recommend spacers for the front & rear? I wouldn't have to worry about rubbing going with 245/40/18 compared to 245/45/18 correct? I live in a pothole/hill populated area in the city.

 

No spacers will be needed as long as you are using the same wheels - many members have upsized to a wider 245 tire without issue on the existing 8" wide OEM 18inchers.

 

Interesting. This is the first mention of 245/45 I've seen as a mostly directly replacement. The threads I read recommended 245/40.

 

What are the advantages or disadvantages for going up a size like this? Would this be a noticeable difference in handling and ride quality also?

 

If you have 19" OEM wheels (F-Sport AWD) - stock tires are 235/40/19 ... upsizing to 245 width gives you more options/choices and no adverse affects.

He mentioned he has 18" OEM wheels (non F Sport AWD)- stock tires are235/45/18..upsizing to slighter wider 245 gives you more tire options and no adverse affects either.

Keeping the height/profile the same in this case at 45 ensures the lowest possible difference in rolling diameter...Helpful tool: https://www.1010tires.com/Tools/Tire...ismetric=False

@MGs350 Pros and Cons: Wider tires give you more tire on the pavement thus better grip for handling/acceleration...but at the expense of a little bit of braking disadvantage and snow/sleet disadvantage. Narrower tires (215/225 wideth) are safer in inclement weather but don't grip as well as wider tires.

Usually upsizing or downsizing helps when selecting tires when it comes time to replace them, especially if you are having a hard time finding all 4 preferred tires in the stock width - upsizing just a touch gets you the same tires all around and often at a cheaper price (i've seen 245 tires cheaper than 235 in many instances!)

 

Got it.. Maybe next time I'll try slightly wider. I just replaced all with stock size dunlop sp sport maxx

 

Ahhhhh, gotcha. My car is an F Sport so I have the OEM 19s; I didn't notice that OP had 18s.