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Recalibrate speedometer? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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YOUR RESEARCHRecalibrate speedometer? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

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Replace 12 year old tires

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I replaced the 12 year old tires that came with my recently purchased 99 boxster.

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Recalibrate speedometer? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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Leading evidence: 'Replace 12 year old tires' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace 12 year old tires' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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Replace 12 year old tires

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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster

I replaced the 12 year old tires that came with my recently purchased 99 boxster.

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Recalibrate speedometer? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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9 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

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POST 1 / ORIGINAL POSTEROriginal post

I replaced the 12 year old tires that came with my recently purchased 99 boxster. The wheels are 18” off a cayman. The tires on the back were 265/40/18. I replaced them with what was suggested by this forum and tire rack. I put 265/35/18. With the 40’s my speedometer was 1 mph off. Now it’s constantly 3 below what my Garmin says. It’s not even a percent of the speed. From 20 mph to 80, 3 mph lower. After reading some posts on this forum 3mph seem to be in the “normal” range. The quick fix would be to go back to 40’s when these need to be replaced. Short of pulling out the instrument cluster and sending it to be recalibrated are there any other methods to fix speedometer?

POST 3Original post

Quotes source post: 596337

The "normal range" is the speedo reading 3 - 4 mph high , not low.

POST 4Original post

Quotes source post: 596388

+1 Who needs a speedo anyways except my wife. Every time we drive I have to reminder her that the speedo displays 25mph over. We aren't going 95, we're only going 70. I so rarely look at the speedo that it doesn't bother me anymore.

POST 5Original post

In 2003 the digital speedometer was moved from the bottom of the center tachometer to the bottom of the speedometer on the left, making it more difficult to look at. I generally keep my phone in a RAM mount on the center of the windshield just above the dash with Waze open and use that for my speedometer.

POST 6Original post

Quotes source post: 596390

LOL !! I gotta remember that one.

POST 7Original post

The dash speedo is merely a suggestion and heavily influenced by tire wear and tire choice. If you *must* know your precise speed +/- 2mph, only trust a GPS receiver.

POST 8Original post

my 99 2.5 tip has a difference of 5mph over compare to phone speed. Tires are all stock sizes per front hood sticker.

POST 9Original post

Quotes source post: 596687

My 99 tip is also 5 over.But I drive off of the tach so ?

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