Aspect Ratio Options.

[EDSELRANGER]

I'm going to be putting another set of tires on my Lacrosse pretty soon. I have the 20 inch wheels that come with 245/40/R20 tires. Those low profile tires handle very well but are of course a bit harsh in the ride department. Does anyone know if it is possible to run/fit a slightly higher profile (50 aspect ratio for example rather than 40) tire? Anyone here tried that?
Sorry if this has been discussed. For some reason, I can't locate the 'Search' function.

 

[MelsRegal]

I'm going to be putting another set of tires on my Lacrosse pretty soon. I have the 20 inch wheels that come with 245/40/R20 tires. Those low profile tires handle very well but are of course a bit harsh in the ride department. Does anyone know if it is possible to run/fit a slightly higher profile (50 aspect ratio for example rather than 40) tire? Anyone here tried that?
Sorry if this has been discussed. For some reason, I can't locate the 'Search' function.

195/50x20 is the same diameter as a 245/40x15, so the answer is no, much too narrow.

 

[EDSELRANGER]

Thank you for the reply. I think "what we've got here is failure to cummunecate" (Apologies to Strother Martin).

The tires I am/was considering would be 245/45/20 or maybe 245/50/20. Same width and rim diameter as stock. The only change would be in the aspect ratio. Since posting this question, I've discovered that an aspect ratio of 50 would definitely make the OD too large to fit properly. Still haven't found any good answers about the 45 aspect ratio.

The only responses so far are warning me about incorrect speedometer readings due to the increased tire diameter. I am not concerned with that. Only want to know if they would fit into the wheel wells without rubbing etc.

Thanks again.

 

[MelsRegal]

Thank you for the reply. I think "what we've got here is failure to cummunecate" (Apologies to Strother Martin).

The tires I am/was considering would be 245/45/20 or maybe 245/50/20. Same width and rim diameter as stock. The only change would be in the aspect ratio. Since posting this question, I've discovered that an aspect ratio of 50 would definitely make the OD too large to fit properly. Still haven't found any good answers about the 45 aspect ratio.

The only responses so far are warning me about incorrect speedometer readings due to the increased tire diameter. I am not concerned with that. Only want to know if they would fit into the wheel wells without rubbing etc.

Thanks again.

The maximum difference before causing speedometer issues which can effect other speed dependant functions, transmission, is 3 percent.
The 245/40x20 versus a 245/50x20 is a 6.9 percent increase in diameter.
The 245/40x20 versus a 245/45x20 is a 3.6 percent increase in diameter.
Tire size tool for comparison

Tire Size Calculator

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tiresize.com

 

[EDSELRANGER]

Thank you again! That Tire Size Calculator you linked is exactly what I needed.

 

[xavier555]

Yeah, you can usually go up a bit on aspect ratio, but you’ll want to double-check clearance in the wheel wells and make sure the overall diameter doesn’t throw off your speedo too much. A 245/45 might be safer than jumping straight to 50. I’ve seen a few Lacrosse owners do it for a smoother ride without big issues. Best bet is to ask a tire shop to run the numbers for you before buying.

 

[02LTD2.0]

Try TireRack.com for guidance on changing tire sizes.

 

[EDSELRANGER]

Try TireRack.com for guidance on changing tire sizes.

Thanks. Been on tire rack site many times. Ordered my last two sets from them.

I have entered all the data and possible options on that site and it just spits out the factory data re wheel/tire size combinations. No data or help there on-line re limitations.

However... I went the old fashioned route and contacted a genuine humanoid at TireRack Customer Service. Helpful tire-tech guy there said it won't work. Even the 1/2 inch increase in unloaded radius will result in rubbing the wheel wells in turns.

So, thanks for the TireRack recommendation. I had not considered actually calling them. Who'd a thunk!