tire fitment question


Old 11-06-10, 10:00 PM
Thread Starter
Join Date: Jun 2005
Location: USA
Posts: 571
tire fitment question

Audi A4 with 235/45R17 tires

Can I install new tires size 245/40R17 with no problem? Please tell me if you know of any problem this would cause or difference this would make. Including speedometer speed displayed vs actual. thanks
Sponsored Links
Old 11-07-10, 04:27 AM
Banned. Rule And/Or Policy Violation
Join Date: Aug 2010
Location: USA
Posts: 560
I donít see any problems with the 245/40R17 in the front. In the rear however, you could have a problem. You may have to cut back the wheel wells, to keep the bottom of the well from hitting the top of the tire. This would be especially true with passengers in the rear seat and when going over bumps. In terms of Speedometer Calibration vs. tire size change, click on the link below.

Speedometer Calibration / Tire Size Change Calculator
Old 11-07-10, 03:05 PM
ukrbyk's Avatar
Join Date: Mar 2010
Location: USA/ Pacific NW
Posts: 3,339
you are swapping to a tire size that is slightly wider and lower. 2nd number is height to width ratio(they just could not have it done in simple HEIGHT, it has to be some ratio). i did quick math, it's about 2 mm difference in height. from rim to the top of the tire. so, overall, from the ground to the uppermost tip of the mounted tire, it will be several mm-s lower.
with a lower tire, overall tire circumference is lesser than one for a taller tire. hence, at the same engine rpm, it will be covering less distance than a taller tire. your spedo is based on drive axle revolutions, for a front wheel drive vehicle. it will still think you are going XX mph, in reality, it will be slightly less.

i do not think with 10mm difference on the tire width you will hit tire well in tight turns, but that's dependent on how far your steering reaches. everything's possible.

btw, any tire shop and many online stores have charts for safe to use tire sizes. discountire, tirerack, and such.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes