Tyres for '74 L48?

G

Gus

CCCUK regional rep
Bought a spare rally wheel from Corvette Kingdom. Scott seemed very surprised that I had fitted 235/70s...….thought that they would cause problems, fouling bodywork etc. However, they seem fine apart from stowing the spare.
He said that 215s were usual and recommended 225s as a max on 70 series rubber. He does sell extended 'carrier bolts'......but as they only give an extra @1.5 inches at the rear of the carrier, I'm not sure they are the answer? Need to get the vehicle on a lift as the two fixings at the front of the carrier can be extended a tad more.
Yes I did ask if there was any discount, and no...I didn't get any, but he seemed a decent and very helpful bloke. Maybe I'll get a bag of sweets with the wheel!
 
Forrest Gump

Forrest Gump

CCCUK regional rep
From the factory the tyre size was GR70-15, the tyre sizing system has changed since then. My understanding is the nearest equivalent is 225/70 R15.
Your 235/70 is wider, that’s fine, but its also a larger diameter by more than 1/2” hence the concern about the tyre rubbing. The speedo may not read quite true either - be aware you may be going faster than the speedo indicates.
Going back to the original problem .....perhaps the larger diameter is preventing the tyre from sitting all the way down into the radius at the bottom of the spare wheel carrier?
 
G

Gus

CCCUK regional rep
May well be correct Forrest....and yes the speedo is @5mph out @70mph. However, I tend to watch the rev counter more, and that is now spot on @3000rpm @70mph.
Should have stuck with my original plan to buy 225s!
Think I will try Roscobbs tip of lowering the pressure very low/flat.....see if it fits, and then carry a tyre inflator....probably a good idea anyway.
 
Chuffer

Chuffer

CCCUK regional rep
Gus said:
Bought a spare rally wheel from Corvette Kingdom. Scott seemed very surprised that I had fitted 235/70s...….thought that they would cause problems, fouling bodywork etc. However, they seem fine apart from stowing the spare.
He said that 215s were usual and recommended 225s as a max on 70 series rubber. He does sell extended 'carrier bolts'......but as they only give an extra @1.5 inches at the rear of the carrier, I'm not sure they are the answer? Need to get the vehicle on a lift as the two fixings at the front of the carrier can be extended a tad more.
Yes I did ask if there was any discount, and no...I didn't get any, but he seemed a decent and very helpful bloke. Maybe I'll get a bag of sweets with the wheel!
Click to expand...
You will definitely get a bag of sweets with your wheel , I have had so many from Scott that all my teeth have fallen out :ROFLMAO:
 
Chuffer

Chuffer

CCCUK regional rep
Gus said:
May well be correct Forrest....and yes the speedo is @5mph out @70mph. However, I tend to watch the rev counter more, and that is now spot on @3000rpm @70mph.
Should have stuck with my original plan to buy 225s!
Think I will try Roscobbs tip of lowering the pressure very low/flat.....see if it fits, and then carry a tyre inflator....probably a good idea anyway.
Click to expand...
The thing is , can you remember the revs for 20 ,30 , 40 , 50 and 60mph cover all the other speed limits we have ? Better stick a `post it ` note on the windscreen and call it a `heads up ` display !:LOL:
On a serious note , it will be worth checking that your 235 / 70`s don`t rub on the chassis rails when steering is on full lock too .
 
Roscobbc

Roscobbc

Moderator
Gus - what is your rear axle ratio? - speedo's on C3's? - does anyone really have the time to look at them on today's road? - TBH keeping nearly 600hp under check and braking is a full time job. The very, very last thing I have time to look at is the speedo - everything else happens so quickly (or is it an age related thing........?) I have an old TomTom mounted on the centre of dashboard just over the upper instruments (in line of sight) purely as an easy reference speed indication.
 
Daytona Vette

Daytona Vette

Well-known user
Chuffer said:
The thing is , can you remember the revs for 20 ,30 , 40 , 50 and 60mph cover all the other speed limits we have ? Better stick a `post it ` note on the windscreen and call it a `heads up ` display !:LOL:
On a serious note , it will be worth checking that your 235 / 70`s don`t rub on the chassis rails when steering is on full lock too .
Click to expand...
My 295s on the front miss the inner wheel arch on lock, ok I may have a different inset but never the less, should be ok and you Chuffer you must be wider on the front?
 
Daytona Vette

Daytona Vette

Well-known user
235s are 14mm taller than 215s on a 70 profile, so Vette sits 7mm higher off the ground and has 7mm less vertical clearance in the wheel arch.
Getting semantic here, forgetting damage to the wheel, always better to have a blow out on a lower profile tyre - low profile: "have I got a puncture"? very high profile: "I had a puncture and hit the barrier"
 
Chuffer

Chuffer

CCCUK regional rep
Daytona Vette said:
235s are 14mm taller than 215s on a 70 profile, so Vette sits 7mm higher off the ground and has 7mm less vertical clearance in the wheel arch.
Getting semantic here, forgetting damage to the wheel, always better to have a blow out on a lower profile tyre - low profile: "have I got a puncture"? very high profile: "I had a puncture and hit the barrier"
Click to expand...
Gus nearly hit both barriers for good measure , I know `cause i was there ( to quote Max Boyce ) 😱
 
Chuffer

Chuffer

CCCUK regional rep
Daytona Vette said:
My 295s on the front miss the inner wheel arch on lock, ok I may have a different inset but never the less, should be ok and you Chuffer you must be wider on the front?
Click to expand...
295 `s on front ! wow thats well wide .What are you running on the rear ? I have 255`s on front and 295 `s the on rear . On full lock , I get just a slight squeek when inner edge of tyre brushes against chassis rail . But that is only when manouvering in tight spaces .
 
G

Gus

CCCUK regional rep
HI Chaps.....the 235s seem to clear everything ok......the Vette has a 3.36 rear end. I also have a1968/69 Aussie Chrysler Valiant V8 sitting on slightly larger modern tyres and Minilites. The gearing of the two cars is pretty much identical, and I have a small printed reminder on the dash giving me fairly exact speed per revs in MPH and Klicks [for when abroad]
 
Daytona Vette

Daytona Vette

Well-known user
Chuffer said:
295 `s on front ! wow thats well wide .What are you running on the rear ? I have 255`s on front and 295 `s the on rear . On full lock , I get just a slight squeek when inner edge of tyre brushes against chassis rail . But that is only when manouvering in tight spaces .
Click to expand...
295s on the back also, sitting on I think (I do have it documented) 10.5s at front and 11.5s at the back, (it has at one time had 335s at the rear). with the 295s all round, no bump steer, no tram lining and the tyres 100% evenly worn across the width of each tyre.
 
Chuffer

Chuffer

CCCUK regional rep
Gus said:
HI Chaps.....the 235s seem to clear everything ok......the Vette has a 3.36 rear end. I also have a1968/69 Aussie Chrysler Valiant V8 sitting on slightly larger modern tyres and Minilites. The gearing of the two cars is pretty much identical, and I have a small printed reminder on the dash giving me fairly exact speed per revs in MPH and Klicks [for when abroad]
Click to expand...
Heads up display on a 1968/68 Aussie ! Wow , that is very advanced for an Antipodean car of that era :LOL:
 
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