please help with upsizing

BG11XV

Forum Member
Joined
Jun 10, 2012
Messages
80
Location
camden nsw
Car Year
2010
Car Model
impreza xv
Transmission
auto,sports shift
hey guys


ok i have a 96 outback

running currently on 205/70 r15 with khumo radials 798 that have lasted me 4 years and still have 50% tread after beating them.


question is i just recieved a free set of wheels from a 09 ugly betty .

that are 215/45 r17 running with continental mc5's

im trying to lower the sidewall as im getting alot of tire roll with the stockies.


BUT THE PROBLEM IS WHEN I DID THE CONVERSION ONLINE ITS SAYING I WILL BE


Speedo Reading Actual Speed
20 mph (32.19 km/h) 18.72 mph (30.13 km/h)
25 mph (40.23 km/h) 23.4 mph (37.66 km/h)
30 mph (48.28 km/h) 28.08 mph (45.19 km/h)
35 mph (56.33 km/h) 32.76 mph (52.73 km/h)
40 mph (64.37 km/h) 37.44 mph (60.26 km/h)
45 mph (72.42 km/h) 42.12 mph (67.79 km/h)
50 mph (80.47 km/h) 46.8 mph (75.32 km/h)
55 mph (88.51 km/h) 51.48 mph (82.86 km/h)
60 mph (96.56 km/h) 56.16 mph (90.39 km/h)
65 mph (104.61 km/h) 60.85 mph (97.92 km/h)


205/70-15 215/45-17 Difference
Diameter inches (mm)26.3 (668) 24.62 (625.3) -1.68 (-42.7) -6.4%
Width inches (mm)8.07 (205) 8.46 (215) 0.39 (10) 4.9%
Circum. inches (mm)82.62 (2098.58) 77.34 (1964.44) -5.28 (-134.15) -6.4%
Sidewall Height inches (mm) 5.65 (143.5) 3.81 (96.75) -1.84 (-46.75) -32.6%
Revolutions per mile (km) 766.87 (476.51) 819.24 (509.05) 52.37 (32.54) 6.8%


IF YOU CAN HELP IT WOULD BE GREAT

I NEED TO KNOW IF I CAN USE THESE AS THEY ARE BRAND NEW TIRES AND IVE TRIED ASKING SHOPS TO SWAP THEM FOR 215/55R17 BUT THEY WONT

THANKS IN ADVANCE
 
Not sure what an "ugly betty" is but if the wheels are compatible I don't see why not. Just use a GPS to track real speed.
 
Oh sorry thats just the models nick name . Like hawk eye and peanut kinda think


Is there any way of calibrating the speedo at all ??
 
Gidday Brian

I would keep your 205/70 15", if I were you. Sell the others ... :iconwink: :biggrin:. Besides, there is a better choice of tyres in 15".

My MY06 has 215/60 16", and is noticeably more comfortable than my SWMBO's MY10 with 225/55 17". Both have OEM alloys.

BTW, the SH doesn't handle better than the SG - if anything it's not as 'tight', because of its considerably bigger and higher body, and different rear suspension (I think ... ).

What tyre pressures are you running?

I have both ours set at around 35 psi F+R. At the recommended 29/28 F:R, the MY06 handles like a barge ...
 
Hey ratbag . Im running 36 All round .

I really need to Reduce the sidewall tho as i drive more to work at cruises atm then offroad .

Im new to tyres . Never had aftermarket before lol
 
G'day again Brian

What's the recommended pressure for your car? I just noticed that it's a '96 Outback.

With Roo1 (my '93 Impreza), I only ever ran the pressures at about 2-3 psi higher than recommended i.e at 32/31 instead of 29/28 - IIRC). Handled like a dream at those pressures. Would have floated like a boat at 35-36 psi!

The Foresters are quite different in that respect. Much bigger, heavier, higher cars than the early Imprezas.

You may find that reducing your tyre pressures to around 2-3 psi above normal recommended helps with your handling problem. But I have little experience with any model Outback ...

You might also find that having a decent 4 wheel alignment done helps enormously. When I fitted the Michelin XM2 on the MY06, I had this done (and checked the frame for squareness). It went from handling like a canal barge to handling extremely well. Each and every one of my wheels were already aligned within spec, but each pointing in a different direction ... so I was walking down the road like a crab ... :( :puke: .
 
Ive tried lower and higher psi . No difference car is square and alligned aswell . Suspension has been rebuilt aswell
 
briangardphoto said:
Is there any way of calibrating the speedo at all ??
Click to expand...


Nope - and illegal I think

If you sort out your OBD scanner per the other thread then it will most likely have a speed display that can be adjusted +/-. The scangauge can do this and I have my scangauge adjusted to show true speed.

(I do sometimes miss my MY'97 OB; very comfortable car)
 
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Ahh ok . Ya that idea went out the window cant do it with ssm :/ i needed obd2 for it
 
check the load rating, Outbacks require higher load ratings than imprezas ( I think)
I find it hard to believe tyre shops won't swap over especially if you are buying a new set from them. Lots of people import tyres from the USA and pay tyre shops to put them on for a fee.
 
You really do need to get the 215/55 tyres for the 17" rims just so your load rating is right. They are a higher profile than the 45's but they still seem to have stiff sidewalls and handle well. The Outback will already have the standard Subaru 7% optimistic speedo and by keeping the 45 profiles on it will only be even more inaccurate. At least you shouldn't get any speeding tickets! Keep trying tyre shops till you can come to some swap deal. They'll want to get the better of you financially though as you'd expect.
 
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